cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A060117 A list of all finite permutations in "PermUnrank3R" ordering. (Inverses of the permutations of A060118.)

Original entry on oeis.org

1, 2, 1, 1, 3, 2, 3, 1, 2, 3, 2, 1, 2, 3, 1, 1, 2, 4, 3, 2, 1, 4, 3, 1, 4, 2, 3, 4, 1, 2, 3, 4, 2, 1, 3, 2, 4, 1, 3, 1, 4, 3, 2, 4, 1, 3, 2, 1, 3, 4, 2, 3, 1, 4, 2, 3, 4, 1, 2, 4, 3, 1, 2, 4, 2, 3, 1, 2, 4, 3, 1, 4, 3, 2, 1, 3, 4, 2, 1, 3, 2, 4, 1, 2, 3, 4, 1, 1, 2, 3, 5, 4, 2, 1, 3, 5, 4, 1, 3, 2, 5, 4, 3, 1, 2
Offset: 0

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Author

Antti Karttunen, Mar 02 2001

Keywords

Comments

PermUnrank3R and PermUnrank3L are slight modifications of unrank2 algorithm presented in Myrvold-Ruskey article.

Examples

			In this table each row consists of A001563[n] permutations of (n+1) terms; i.e., we have (1/) 2,1/ 1,3,2; 3,1,2; 3,2,1; 2,3,1/ 1,2,4,3; 2,1,4,3;
Append to each an infinite number of fixed terms and we get a list of rearrangements of natural numbers, but with only a finite number of terms permuted:
1/2,3,4,5,6,7,8,9,...
2,1/3,4,5,6,7,8,9,...
1,3,2/4,5,6,7,8,9,...
3,1,2/4,5,6,7,8,9,...
3,2,1/4,5,6,7,8,9,...
2,3,1/4,5,6,7,8,9,...
1,2,4,3/5,6,7,8,9,...
2,1,4,3/5,6,7,8,9,...
		

Crossrefs

A060119 = Positions of these permutations in the "canonical list" A055089 (where also the rest of procedures can be found). A060118 gives position of the inverse permutation of each and A065183 positions after Foata transform.
Inversion vectors: A064039.

Programs

  • Maple
    with(group); permul := (a,b) -> mulperms(b,a); PermUnrank3R := proc(r) local n; n := nops(factorial_base(r)); convert(PermUnrank3Raux(n+1,r,[]),'permlist',1+(((r+2) mod (r+1))*n)); end; PermUnrank3Raux := proc(n,r,p) local s; if(0 = r) then RETURN(p); else s := floor(r/((n-1)!)); RETURN(PermUnrank3Raux(n-1, r-(s*((n-1)!)), permul(p,[[n,n-s]]))); fi; end;

Formula

[seq(op(PermUnrank3R(j)), j=0..)]; (Maple code given below)

A059590 Numbers obtained by reinterpreting base-2 representation of n in the factorial base: a(n) = Sum_{k>=0} A030308(n,k)*A000142(k+1).

Original entry on oeis.org

0, 1, 2, 3, 6, 7, 8, 9, 24, 25, 26, 27, 30, 31, 32, 33, 120, 121, 122, 123, 126, 127, 128, 129, 144, 145, 146, 147, 150, 151, 152, 153, 720, 721, 722, 723, 726, 727, 728, 729, 744, 745, 746, 747, 750, 751, 752, 753, 840, 841, 842, 843, 846, 847, 848, 849, 864, 865
Offset: 0

Views

Author

Henry Bottomley, Jan 24 2001

Keywords

Comments

Numbers that are sums of distinct factorials (0! and 1! not treated as distinct).
Complement of A115945; A115944(a(n)) > 0; A115647 is a subsequence. - Reinhard Zumkeller, Feb 02 2006
A115944(a(n)) = 1. - Reinhard Zumkeller, Dec 04 2011
From Tilman Piesk, Jun 04 2012: (Start)
The inversion vector (compare A007623) of finite permutation a(n) (compare A055089, A195663) has only zeros and ones. Interpreted as a binary number it is 2*n (or n when the inversion vector is defined without the leading 0).
The inversion set of finite permutation a(n) interpreted as a binary number (compare A211362) is A211364(n).
(End)

Examples

			128 is in the sequence since 5! + 3! + 2! = 128.
a(22) = 128. a(22) = a(6) + (1 + floor(log(16) / log(2)))! = 8 + 5! = 128. Also, 22 = 10110_2. Therefore, a(22) = 1 * 5! + 0 * 4! + 1 * 3! + 1 + 2! + 0 * 0! = 128. - _David A. Corneth_, Aug 21 2016
		

Crossrefs

Indices of zeros in A257684.
Cf. A275736 (left inverse).
Cf. A025494, A060112 (subsequences).
Subsequence of A060132, A256450 and A275804.
Other sequences that are built by replacing 2^k in the binary representation with other numbers: A029931 (naturals), A089625 (primes), A022290 (Fibonacci), A197433 (Catalans), A276091 (n*n!), A275959 ((2n)!/2). Cf. also A276082 & A276083.

Programs

  • Haskell
    import Data.List (elemIndices)
    a059590 n = a059590_list !! n
    a059590_list = elemIndices 1 $ map a115944 [0..]
    -- Reinhard Zumkeller, Dec 04 2011
    
  • Maple
    [seq(bin2facbase(j),j=0..64)]; bin2facbase := proc(n) local i; add((floor(n/(2^i)) mod 2)*((i+1)!),i=0..floor_log_2(n)); end;
    floor_log_2 := proc(n) local nn,i; nn := n; for i from -1 to n do if(0 = nn) then RETURN(i); fi; nn := floor(nn/2); od; end;
    # next Maple program:
    a:= n-> (l-> add(l[j]*j!, j=1..nops(l)))(Bits[Split](n)):
    seq(a(n), n=0..57);  # Alois P. Heinz, Aug 12 2025
  • Mathematica
    a[n_] :=  Reverse[id = IntegerDigits[n, 2]].Range[Length[id]]!; Table[a[n], {n, 0, 60}] (* Jean-François Alcover, Jun 19 2012, after Philippe Deléham *)
  • PARI
    a(n) = if(n>0, a(n-msb(n)) + (1+logint(n,2))!, 0)
    msb(n) = 2^#binary(n)>>1
    {my(b = binary(n)); sum(i=1,#b,b[i]*(#b+1-i)!)} \\ David A. Corneth, Aug 21 2016
    
  • Python
    def facbase(k, f):
        return sum(f[i] for i, bi in enumerate(bin(k)[2:][::-1]) if bi == "1")
    def auptoN(N): # terms up to N factorial-base digits; 13 generates b-file
        f = [factorial(i) for i in range(1, N+1)]
        return list(facbase(k, f) for k in range(2**N))
    print(auptoN(5)) # Michael S. Branicky, Oct 15 2022

Formula

G.f. 1/(1-x) * Sum_{k>=0} (k+1)!*x^2^k/(1+x^2^k). - Ralf Stephan, Jun 24 2003
a(n) = Sum_{k>=0} A030308(n,k)*A000142(k+1). - Philippe Deléham, Oct 15 2011
From Antti Karttunen, Aug 19 2016: (Start)
a(0) = 0, a(2n) = A153880(a(n)), a(2n+1) = 1+A153880(a(n)).
a(n) = A225901(A276091(n)).
a(n) = A276075(A019565(n)).
a(A275727(n)) = A276008(n).
A275736(a(n)) = n.
A276076(a(n)) = A019565(n).
A007623(a(n)) = A007088(n).
(End)
a(n) = a(n - mbs(n)) + (1 + floor(log(n) / log(2)))!. - David A. Corneth, Aug 21 2016

Extensions

Name changed (to emphasize the functional nature of the sequence) with the old definition moved to the comments by Antti Karttunen, Aug 21 2016

A030298 List of permutations of 1,2,3,...,n for n=1,2,3,..., in lexicographic order.

Original entry on oeis.org

1, 1, 2, 2, 1, 1, 2, 3, 1, 3, 2, 2, 1, 3, 2, 3, 1, 3, 1, 2, 3, 2, 1, 1, 2, 3, 4, 1, 2, 4, 3, 1, 3, 2, 4, 1, 3, 4, 2, 1, 4, 2, 3, 1, 4, 3, 2, 2, 1, 3, 4, 2, 1, 4, 3, 2, 3, 1, 4, 2, 3, 4, 1, 2, 4, 1, 3, 2, 4, 3, 1, 3, 1, 2, 4, 3, 1, 4, 2, 3, 2, 1, 4, 3, 2, 4, 1, 3, 4, 1, 2, 3, 4, 2, 1, 4, 1, 2, 3, 4, 1, 3, 2, 4, 2
Offset: 1

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Author

Keywords

Comments

Contains every finite sequence of distinct numbers, infinitely many times.

Examples

			The permutations can be written as
  1,
  12, 21,
  123, 132, 213, 231, 312, 321, etc.
Write them in order and insert commas.
		

Crossrefs

A030299 gives the initial portion of these same permutations as decimally encoded numbers.
Cf. A001563 (row lengths), A001286 (row sums).
Cf. A030496 for another ordering.
The same information is essentially given in A055089, but in more compact way, by skipping those permutations which start with a fixed element (cf. A220696).
A220660(n) tells the zero-based rank r of the n-th permutation in this sequence, among all finite permutations of the same size.
A220663(n) tells the zero-based position (from the left) of that a(n) in that permutation of rank r.
A084557(n) tells that the n-th term a(n) belongs to the a(n):th lexicographically ordered permutation from the start (its "global rank").
A220660(A084557(n)) tells the "local rank" of the permutation (amongst the permutations of the same size) to which the n-th term a(n) belongs.
(A130664(n),A084555(n)) = (1,1),(2,3),(4,5),(6,8),(9,11),(12,14),... gives the starting and ending offsets of the n-th permutation in this list.

Programs

  • Haskell
    import Data.List (permutations, sort)
    a030298 n k = a030298_tabf !! (n-1) (k-1)
    a030298_row = concat . sort . permutations . enumFromTo 1
    a030298_tabf = map a030298_row [1..]
    -- Reinhard Zumkeller, Mar 29 2012
    (MIT/GNU Scheme, with Antti Karttunen's intseq-library):
    ;; Note that in Scheme, vector indexing is zero-based.
    ;; Requires also A055089permvec from A055089.
    (define (A030298 n) (vector-ref (A030298permvec (A084556 (A084557 n)) (A220660 (A084557 n))) (A220663 n)))
    (define (A030298permvec size rank) (vector-reverse (vector1invert (A055089permvec size rank))))
    (define (vector1invert vec) (make-initialized-vector (vector-length vec) (lambda (i) (1+ (- (vector-length vec) (vector-ref vec i))))))
    (define (vector-reverse vec) (make-initialized-vector (vector-length vec) (lambda (i) (vector-ref vec (- (vector-length vec) i 1)))))
    
  • Mathematica
    f[n_] := Permutations[Range@ n, {n}]; Array[f, 4] // Flatten (* Robert G. Wilson v, Dec 18 2012 *)
  • Python
    from itertools import permutations, count, chain, islice
    def A030298_gen(): # generator of terms
        return chain.from_iterable(p for l in count(2) for p in permutations(range(1,l)))
    A030298_list = list(islice(A030298_gen(),30)) # Chai Wah Wu, Mar 21 2022

Formula

Start with 1, then 12 and 21, then the 6 permutations of 123 in lexical order: 123, 132, 213, 231, 312, 321 and so on.

Extensions

Entry revised by N. J. A. Sloane, Feb 02 2006
Keyword tabf added by Reinhard Zumkeller, Mar 29 2012

A060118 A list of all finite permutations in "PermUnrank3L" ordering. (Inverses of the permutations of A060117.)

Original entry on oeis.org

1, 2, 1, 1, 3, 2, 2, 3, 1, 3, 2, 1, 3, 1, 2, 1, 2, 4, 3, 2, 1, 4, 3, 1, 3, 4, 2, 2, 3, 4, 1, 3, 2, 4, 1, 3, 1, 4, 2, 1, 4, 3, 2, 2, 4, 3, 1, 1, 4, 2, 3, 2, 4, 1, 3, 3, 4, 1, 2, 3, 4, 2, 1, 4, 2, 3, 1, 4, 1, 3, 2, 4, 3, 2, 1, 4, 3, 1, 2, 4, 2, 1, 3, 4, 1, 2, 3, 1, 2, 3, 5, 4, 2, 1, 3, 5, 4, 1, 3, 2, 5, 4, 2, 3, 1
Offset: 0

Views

Author

Antti Karttunen, Mar 02 2001

Keywords

Comments

In contrast to PermUnrank3R (A060117), PermUnrank3L applies each successive transposition from the left, not from the right, thus producing the inverse (permutation) of what PermUnrank3R would produce.

Examples

			In this table each row consists of A001563[n] permutations of (n+1) terms;
Append to each an infinite number of fixed terms and we get a list of rearrangements of natural numbers, but with only a finite number of terms permuted:
1/2,3,4,5,6,7,8,9,...
2,1/3,4,5,6,7,8,9,...
1,3,2/4,5,6,7,8,9,...
2,3,1/4,5,6,7,8,9,...
3,2,1/4,5,6,7,8,9,...
3,1,2/4,5,6,7,8,9,...
1,2,4,3/5,6,7,8,9,...
2,1,4,3/5,6,7,8,9,...
		

Crossrefs

A060120 = Positions of these permutations in the "canonical list" A055089. Cf. also A060117.

Programs

  • Maple
    with(group); permul := (a,b) -> mulperms(b,a); PermUnrank3L := proc(r) local n; n := nops(factorial_base(r)); convert(PermUnrank3Laux(n+1,r,[]),'permlist',1+(((r+2) mod (r+1))*n)); end; PermUnrank3Laux := proc(n,r,p) local s; if(0 = r) then RETURN(p); else s := floor(r/((n-1)!)); RETURN(PermUnrank3Laux(n-1, r-(s*((n-1)!)), permul([[n,n-s]],p))); fi; end;

Formula

[seq(op(PermUnrank3L(j)), j=0..)]; (Maple code given below)

A030299 Decimal representation of permutations of lengths 1, 2, 3, ... arranged lexicographically.

Original entry on oeis.org

1, 12, 21, 123, 132, 213, 231, 312, 321, 1234, 1243, 1324, 1342, 1423, 1432, 2134, 2143, 2314, 2341, 2413, 2431, 3124, 3142, 3214, 3241, 3412, 3421, 4123, 4132, 4213, 4231, 4312, 4321, 12345, 12354, 12435, 12453, 12534, 12543, 13245, 13254, 13425
Offset: 1

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Author

Keywords

Comments

This is a list of the permutations in "one-line" notation (cf. Dixon and Mortimer, p. 2). The i-th element of the string is the image of i under the permutation. For example 231 is the permutation that sends 1 to 2, 2 to 3, and 3 to 1. - N. J. A. Sloane, Apr 12 2014
Precise definition of the term "Decimal representation" (required for indices n>409113): Numbers N(s) = Sum_{i=1..m} s(i)*10^(m-i), where s runs over the permutations of (1,...,m), and m=1,2,3,.... This also defines the "lexicographical" order: Obviously 21 comes before 123, etc. The lexicographical order of the permutations, for given m, is the same as the natural order of the numbers N(s). - M. F. Hasler, Jan 28 2013
An alternate variant, using concatenation of the permutations, is very clumsy once the length exceeds 9. For example, after 987654321 (= A030299(409113), where 409113 = A007489(9)) we would get 12345678910, 12345678109, ... In A030298 this problem has been avoided by listing the elements of permutations as separate terms. [Edited by M. F. Hasler, Jan 28 2013]
Sequence A051845 is a base-independent version of this sequence: Permutations of 1...m are considered as numbers written in base m+1. - M. F. Hasler, Jan 28 2013

References

  • John D. Dixon and Brian Mortimer, Permutation groups. Graduate Texts in Mathematics, 163. Springer-Verlag, New York, 1996. xii+346 pp. ISBN: 0-387-94599-7 MR1409812 (98m:20003).

Crossrefs

A007489(n) gives the position (index) of the term corresponding to last permutation of n elements: (n,n-1,...,1).
The first differences A220664 has interesting fractal structure, see A219664 and A217626.
Cf. also A030298, A055089, A060117, A181073, A352991 (by concatenation).
See A240763 for preferential arrangements.

Programs

  • Maple
    seq(seq(add(s[i]*10^(m-i),i=1..m),s=combinat:-permute([$1..m])),m=1..5); # Robert Israel, Oct 14 2015
  • Mathematica
    Flatten @ Table[FromDigits /@ Permutations[Table[i,{i,n}]],{n,9}] (* For first 409113 terms; Zak Seidov, Oct 03 2015 *)
  • PARI
    is_A030299(n)={ (n>1234567890 & print("maybe")) || vecsort(digits(n))==vector(#Str(n),i,i) } \\ /* use digits(n)=eval(Vec(Str(n))) in older versions lacking this function */ \\ M. F. Hasler, Dec 12 2012
    (MIT/GNU Scheme)
    ;; Antti Karttunen, Dec 18 2012
    ;; Requires also code from A030298 and A055089:
    (define (A030299 n) (vector->base-k (A030298permvec (A084556 n) (A220660 n)) 10))
    (define (vector->base-k vec k) (let loop ((i 0) (s 0)) (cond ((= (vector-length vec) i) s) ((>= (vector-ref vec i) k) (error (format #f "Cannot interpret vector ~a in base ~a!" vec k))) (else (loop (+ i 1) (+ (* k s) (vector-ref vec i)))))))
    
  • Python
    from itertools import permutations
    def pmap(s, m): return sum(s[i-1]*10**(m-i) for i in range(1, len(s)+1))
    def agen():
      m = 1
      while True:
        for s in permutations(range(1, m+1)): yield pmap(s, m)
        m += 1
    def aupton(terms):
      alst, g = [], agen()
      while len(alst) < terms: alst += [next(g)]
      return alst
    print(aupton(42)) # Michael S. Branicky, Jan 12 2021

Extensions

Edited by N. J. A. Sloane, Feb 23 2010

A051683 Triangle read by rows: T(n,k) = n!*k.

Original entry on oeis.org

1, 2, 4, 6, 12, 18, 24, 48, 72, 96, 120, 240, 360, 480, 600, 720, 1440, 2160, 2880, 3600, 4320, 5040, 10080, 15120, 20160, 25200, 30240, 35280, 40320, 80640, 120960, 161280, 201600, 241920, 282240, 322560, 362880, 725760, 1088640, 1451520, 1814400, 2177280, 2540160, 2903040, 3265920
Offset: 1

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Author

Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de)

Keywords

Comments

Numbers with only one nonzero digit when written in factorial base. - Franklin T. Adams-Watters, Nov 28 2011
In other words, numbers m such that A034968(m) = A099563(m). - Antti Karttunen, Jul 02 2013
When the numbers denote finite permutations (as row numbers of A055089) these are the circular shifts to the right within an interval. The subsequence A001563 denotes the circular shifts that start with the first element. Compare A211370 for circular shifts to the left. - Tilman Piesk, Apr 29 2017

Examples

			Table begins
   1;
   2,  4;
   6, 12, 18;
  24, 48, 72, 96; ...
		

Crossrefs

Programs

  • Haskell
    a051683 n k = a051683_tabl !! (n-1) !! (k-1)
    a051683_row n = a051683_tabl !! (n-1)
    a051683_tabl = map fst $ iterate f ([1], 2) where
       f (row, n) = (row' ++ [head row' + last row'], n + 1) where
         row' = map (* n) row
    -- Reinhard Zumkeller, Mar 09 2012
    
  • Magma
    [[Factorial(n)*k: k in [1..n]]: n in [1..15]]; // Vincenzo Librandi, Jun 15 2015
    
  • Mathematica
    T[n_, k_] := n!*k; Flatten[Table[T[n, k], {n, 9}, {k, n}]] (* Jean-François Alcover, Apr 22 2011 *)
  • PARI
    for(n=1,10, for(k=1,n, print1(n!*k, ", "))) \\ G. C. Greubel, Mar 27 2018
    
  • Python
    from math import isqrt, factorial, comb
    def A051683(n): return factorial(a:=(m:=isqrt(k:=n<<1))+(k>m*(m+1)))*(n-comb(a,2)) # Chai Wah Wu, Jun 25 2025
  • Scheme
    (define (A051683 n) (* (A000142 (A002024 n)) (A002260 n))) ;; Antti Karttunen, Jul 02 2013
    

Formula

T(n,k) = A000142(A002024(n)) * A002260(n,k) = A002024(n)! * A002260(n,k) - Antti Karttunen, Jul 02 2013
Sum_{n>=1} 1/a(n) = e * (gamma - Ei(-1)) = A347952. - Amiram Eldar, Oct 13 2024

A195663 Array read by antidiagonals: Consecutive finite permutations of positive integers in reverse colexicographic order.

Original entry on oeis.org

1, 2, 2, 3, 1, 1, 4, 3, 3, 3, 5, 4, 2, 1, 2, 6, 5, 4, 2, 3, 3, 7, 6, 5, 4, 1, 2, 1, 8, 7, 6, 5, 4, 1, 2, 2, 9, 8, 7, 6, 5, 4, 4, 1, 1, 10, 9, 8, 7, 6, 5, 3, 4, 4, 4, 11, 10, 9, 8, 7, 6, 5, 3, 2, 1, 2, 12, 11, 10, 9, 8, 7, 6, 5, 3, 2, 4, 4, 13, 12, 11, 10, 9, 8, 7, 6, 5, 3, 1, 2, 1, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 3, 1, 3, 3
Offset: 0

Views

Author

Tilman Piesk, Sep 22 2011

Keywords

Comments

Row n is the n-th finite permutation of {1,2,3,4,...}.

Examples

			The first 24 permutations of positive integers in rev colex order:
00  -->  1 2 3 4 5 6 7 8 ...
01  -->  2 1 3 4 ...
02  -->  1 3 2 4 ...
03  -->  3 1 2 4 ...
04  -->  2 3 1 4 ...
05  -->  3 2 1 4 ...
06  -->  1 2 4 3 ...
07  -->  2 1 4 3 ...
08  -->  1 4 2 3 ...
09  -->  4 1 2 3 ...
10  -->  2 4 1 3 ...
11  -->  4 2 1 3 ...
12  -->  1 3 4 2 ...
13  -->  3 1 4 2 ...
14  -->  1 4 3 2 ...
15  -->  4 1 3 2 ...
16  -->  3 4 1 2 ...
17  -->  4 3 1 2 ...
18  -->  2 3 4 1 ...
19  -->  3 2 4 1 ...
20  -->  2 4 3 1 ...
21  -->  4 2 3 1 ...
22  -->  3 4 2 1 ...
23  -->  4 3 2 1 ...
		

Crossrefs

Cf. A055089 (a very compact representation of these permutations).
Cf. A195664 (same for nonnegative integers, so all entries are smaller by 1).

Formula

a(n) = A195664(n)+1.

A060112 Sums of nonconsecutive factorial numbers.

Original entry on oeis.org

0, 1, 2, 6, 7, 24, 25, 26, 120, 121, 122, 126, 127, 720, 721, 722, 726, 727, 744, 745, 746, 5040, 5041, 5042, 5046, 5047, 5064, 5065, 5066, 5160, 5161, 5162, 5166, 5167, 40320, 40321, 40322, 40326, 40327, 40344, 40345, 40346, 40440, 40441, 40442
Offset: 1

Views

Author

Antti Karttunen, Mar 01 2001

Keywords

Comments

Zeckendorf (Fibonacci) expansion of n (A003714) reinterpreted as a factorial expansion.
Also positions in A055089, A060117 and A060118 of the permutations that are composed of disjoint adjacent transpositions only. (That these positions are same can be seen by comparing algorithms PermRevLexUnrankAMSD, PermUnrank3R, PermUnrank3L in the respective sequences). Thus also positions of the fixed terms in A065181-A065184. See comment at A065163.
Written as disjoint cycles the permutations are: (), (1 2), (2 3), (3 4), (1 2)(3 4), (4 5), (1 2)(4 5), (2 3)(4 5), etc. Apart from the first one (the identity), these are the only kind of permutations used in campanology when moving from one "change" to next.

Examples

			Zeckendorf Expansions of first few natural numbers and the corresponding values when interpreted as factorial expansions: 0 = 0 = 0, 1 = 1 = 1, 2 = 10 = 2, 3 = 100 = 6, 4 = 101 = 7, 5 = 1000 = 24, 6 = 1001 = 25, 7 = 1010 = 26, 8 = 10000 = 120, etc.,
		

Crossrefs

Subset of A059590. Cf. also A001611, A064640.
For PermRevLexRank, see A056019, for fibbinary see A048679 and A003714.

Programs

  • Maple
    CampanoPerm := proc(n) local z,p,i; p := []; z := fibbinary(n); i := 1; while(z > 0) do if(1 = (z mod 2)) then p := permul(p,[[i,i+1]]); fi; i := i+1; z := floor(z/2); od; RETURN(convert(p,'permlist',i)); end;
  • Mathematica
    With[{b = MixedRadix[Range[12, 2, -1]]}, FromDigits[#, b] & /@ Select[Tuples[{0, 1}, 8], SequenceCount[#, {1, 1}] == 0 &]] (* Michael De Vlieger, Jun 26 2017 *)
  • PARI
    fill(lim,k,val)=if(k>#f, return); my(t=val+f[k]); if(t<=lim, listput(v,t); fill(lim,k+2,t)); fill(lim,k+1,val)
    list(lim)=my(k,t=1); local(f=List(),v=List([0])); while((t*=k++)<=lim, listput(f,t)); f=Vecrev(f); fill(lim,1,0); Set(v) \\ Charles R Greathouse IV, Jun 25 2017
    
  • PARI
    first(n) = my(res = [0, 1], k = 1, t = 1, p = 1); while(#res < n, k++; t++; p *= t; res = concat(res, vector(fibonacci(k), i, res[i]+p))); vector(n, i, res[i]) \\ David A. Corneth, Jun 26 2017

Formula

a(n) = PermRevLexRank(CampanoPerm(n))
a(A001611(n)) = (n-1)! for n > 2. - David A. Corneth, Jun 25 2017

A227148 Numbers k for which the sum of digits is even when k is written in the factorial base (A007623).

Original entry on oeis.org

0, 3, 4, 7, 8, 11, 12, 15, 16, 19, 20, 23, 25, 26, 29, 30, 33, 34, 37, 38, 41, 42, 45, 46, 48, 51, 52, 55, 56, 59, 60, 63, 64, 67, 68, 71, 73, 74, 77, 78, 81, 82, 85, 86, 89, 90, 93, 94, 96, 99, 100, 103, 104, 107, 108, 111, 112, 115, 116, 119, 121, 122, 125
Offset: 1

Views

Author

Antti Karttunen, Jul 02 2013

Keywords

Comments

Numbers k for which minimal number of factorials needed to add to get k is even.
This sequence offers one possible analog to A001969 (evil numbers) in factorial base system. A227130 gives another kind of analog.
In each range [0,n!-1] exactly half of the integers are found in this sequence, and the other half of them are found in the complement, A227149.
The sequence gives the positions of even permutations in the tables A055089 and A195663; and equivalently, the positions of even numbers in A055091.

Crossrefs

Complement: A227149. Cf. also A001969, A034968, A227130.

Programs

  • Mathematica
    q[n_] := Module[{k = n, m = 2, s = 0, r}, While[{k, r} = QuotientRemainder[k, m]; k != 0|| r != 0, s += r; m++]; EvenQ[s]]; Select[Range[0, 125], q] (* Amiram Eldar, Jan 24 2024 *)

A290095 a(n) = A275725(A060126(n)); prime factorization encodings of cycle-polynomials computed for finite permutations listed in reversed colexicographic ordering.

Original entry on oeis.org

2, 4, 18, 8, 8, 12, 150, 100, 54, 16, 16, 24, 54, 16, 90, 40, 36, 16, 16, 24, 40, 60, 16, 36, 1470, 980, 882, 392, 392, 588, 750, 500, 162, 32, 32, 48, 162, 32, 270, 80, 108, 32, 32, 48, 80, 120, 32, 72, 750, 500, 162, 32, 32, 48, 1050, 700, 378, 112, 112, 168, 450, 200, 162, 32, 32, 72, 200, 300, 32, 48, 108, 32, 162, 32, 270, 80, 108, 32, 378, 112, 630, 280
Offset: 0

Views

Author

Antti Karttunen, Aug 17 2017

Keywords

Comments

In this context "cycle-polynomials" are single-variable polynomials where the coefficients (encoded with the exponents of prime factorization of n) are equal to the lengths of cycles in the permutation listed with index n in table A055089 (A195663). See the examples.

Examples

			Consider the first eight permutations (indices 0-7) listed in A055089:
  1 [Only the first 1-cycle explicitly listed thus a(0) = 2^1 = 2]
  2,1 [One transposition (2-cycle) in beginning, thus a(1) = 2^2 = 4]
  1,3,2 [One fixed element in beginning, then transposition, thus a(2) = 2^1 * 3^2 = 18]
  3,1,2 [One 3-cycle, thus a(3) = 2^3 = 8]
  2,3,1 [One 3-cycle, thus a(4) = 2^3 = 8]
  3,2,1 [One transposition jumping over a fixed element, a(5) = 2^2 * 3^1 = 12]
  1,2,4,3 [Two 1-cycles, then a 2-cycle, thus a(6) = 2^1 * 3^1 * 5^2 = 150].
  2,1,4,3 [Two 2-cycles, not crossed, thus a(7) = 2^2 * 5^2 = 100].
		

Crossrefs

Formula

a(n) = A275725(A060126(n)).
Other identities:
A046523(a(n)) = A290096(n).
A056170(a(n)) = A055090(n).
A046660(a(n)) = A055091(n).
A072411(a(n)) = A055092(n).
A275812(a(n)) = A055093(n).
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