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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A178477 Permutations of 1234567: Numbers having each of the decimal digits 1,...,7 exactly once, and no other digit.

Original entry on oeis.org

1234567, 1234576, 1234657, 1234675, 1234756, 1234765, 1235467, 1235476, 1235647, 1235674, 1235746, 1235764, 1236457, 1236475, 1236547, 1236574, 1236745, 1236754, 1237456, 1237465, 1237546, 1237564, 1237645, 1237654
Offset: 1

Views

Author

M. F. Hasler, Oct 09 2010

Keywords

Comments

It would be nice to have a simple explicit formula for the n-th term.
Contains A000142(7) = 5040 terms. - R. J. Mathar, Apr 08 2011
An efficient procedure for generating the n-th term of this sequence can be found at A178475. - Nathaniel Johnston, May 19 2011

Crossrefs

Programs

  • Mathematica
    FromDigits/@Take[Permutations[Range[7]],50] (* Harvey P. Dale, Nov 11 2012 *)
  • PARI
    is_A178477(x)= { vecsort(Vec(Str(x)))==Vec("1234567") }

A178478 Permutations of 12345678: Numbers having each of the decimal digits 1..8 exactly once, and no other digit.

Original entry on oeis.org

12345678, 12345687, 12345768, 12345786, 12345867, 12345876, 12346578, 12346587, 12346758, 12346785, 12346857, 12346875, 12347568, 12347586, 12347658, 12347685, 12347856, 12347865, 12348567, 12348576, 12348657, 12348675, 12348756, 12348765
Offset: 1

Views

Author

M. F. Hasler, Oct 09 2010

Keywords

Comments

It would be nice to have a simple explicit formula for the n-th term.
An efficient procedure for generating the n-th term of this sequence can be found at A178475. - Nathaniel Johnston, May 19 2011

Crossrefs

Programs

  • Mathematica
    Take[FromDigits/@Permutations[Range[8]],40] (* Harvey P. Dale, Oct 29 2014 *)
  • PARI
    is_A178478(x)= { vecsort(Vec(Str(x)))==Vec("12345678") }
    
  • PARI
    A178478(n)={my(b=vector(7,k,1+(n-1)%(k+1)!\k!),t=b[7], d=vector(7,i,i+(i>=t)));for(i=1,6,t=10*t+d[b[7-i]]; d=vecextract(d,Str("^"b[7-i]))); t*10+d[1]} \\ - M. F. Hasler (following N. Johnston's comment), Jan 10 2012

A220696 The positions of those permutations in A030298 where the first element is one (fixed).

Original entry on oeis.org

1, 2, 4, 5, 10, 11, 12, 13, 14, 15, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179
Offset: 1

Views

Author

Antti Karttunen, Dec 17 2012

Keywords

Comments

Correspondingly gives the positions of those terms in A030299 whose first digit is 1, as long as the decimal encoding system employed is valid.

Crossrefs

Complement: A220656. Cf. A072795.

Formula

a(1)=1; and for n>1, a(n)=A220695(n-1)+1.

A305701 Nonnegative integers whose decimal digits span an initial interval of {0,...,9}.

Original entry on oeis.org

0, 10, 100, 101, 102, 110, 120, 201, 210, 1000, 1001, 1002, 1010, 1011, 1012, 1020, 1021, 1022, 1023, 1032, 1100, 1101, 1102, 1110, 1120, 1200, 1201, 1202, 1203, 1210, 1220, 1230, 1302, 1320, 2001, 2010, 2011, 2012, 2013, 2021, 2031, 2100, 2101, 2102, 2103
Offset: 1

Views

Author

Gus Wiseman, Jun 08 2018

Keywords

Crossrefs

Programs

  • Maple
    filter:= proc(n) local L;
      L:= convert(convert(n,base,10),set);
      L = {$0..max(L)}
    end proc:
    select(filter, [$0..3000]); # Robert Israel, Jun 10 2018
  • Mathematica
    Select[Range[0,10000],Union[IntegerDigits[#]]==Range[0,Max[IntegerDigits[#]]]&]
  • PARI
    isok(n) = if (n==0, return (1)); my(d=Set(digits(n))); (vecmin(d) == 0) && (vecmax(d) == #d - 1); \\ Michel Marcus, Jul 05 2018

A305714 Number of finite sequences of positive integers of length n that are polydivisible and strictly pandigital.

Original entry on oeis.org

1, 1, 1, 2, 0, 0, 2, 0, 1, 1, 1
Offset: 0

Views

Author

Gus Wiseman, Jun 08 2018

Keywords

Comments

A sequence q of length k is strictly pandigital if it is a permutation of {1,2,...,k}. It is polydivisible if Sum_{i = 1...m} 10^(m - i) * q_i is a multiple of m for all 1 <= m <= k.

Examples

			Sequence of sets of n-digit numbers that are weakly polydivisible and strictly pandigital is (with A = 10):
  {0}
  {1}
  {12}
  {123,321}
  {}
  {}
  {123654,321654}
  {}
  {38165472}
  {381654729}
  {381654729A}
		

Crossrefs

A181073 Permutations of lengths 1,2,3,... arranged lexicographically that are relatively prime to 30.

Original entry on oeis.org

1, 1243, 1423, 2143, 2341, 2413, 2431, 3241, 3421, 4123, 4213, 4231, 4321, 1234567, 1234657, 1235467, 1235647, 1236457, 1236547, 1243567, 1243657, 1245367, 1245637, 1245673, 1245763, 1246357, 1246537, 1246573, 1246753
Offset: 1

Views

Author

Marco Ripà, Jan 23 2011

Keywords

Comments

Numbers whose digits are permutations of (1,2,3,4,...,n) for some n >= 1, for which the first 3 primes (2,3,5) do not appear in their factorization. This constitutes the smallest subset of A030299 for which it's possible to synthesize a compact formula to express the generic term: it contains every prime number already in A030299.
In fact it corresponds to the subset of the terms of A030299 constructed from the concatenation of k:=1+3*i (for i >= 0) elements belonging to (1,2,3,4,...,n) that are congruent in modulo 10 to (1,3,7,9).

Crossrefs

Programs

  • Mathematica
    f[n_] := Select[ FromDigits@ # & /@ Permutations@ Range@ n, Mod[#, 2] != 0 && Mod[#, 3] != 0 && Mod[#, 5] != 0 &]; Take[ Flatten@ Array[f, 7], 35]

A305712 Polydivisible nonnegative integers whose decimal digits span an initial interval of {0,...,9}.

Original entry on oeis.org

0, 10, 102, 120, 201, 1020, 1200, 2012, 10200, 12000, 12320, 20120, 32120, 102000, 120000, 123204, 321204, 1024023, 1200003, 1232042, 1444023, 2220001, 3212041, 10240232, 12000032, 12320424, 14440232, 32125240, 50165432
Offset: 0

Views

Author

Gus Wiseman, Jun 08 2018

Keywords

Comments

A number with decimal digit sequence {q_1, ..., q_k} is polydivisible if Sum_{i = 1...m} 10^(m - i) * q_i is a multiple of m for all 1 <= m <= k.

References

  • Matt Parker, Things to make and do in the fourth dimension, 2015, pages 7-9.

Crossrefs

Programs

  • Mathematica
    polyQ[q_]:=And@@Table[Divisible[FromDigits[Take[q,k]],k],{k,Length[q]}];
    normseqs[n_]:=Join@@Permutations/@Function[s,Array[Count[s,y_/;y<=#]+1&,n]]/@Subsets[Range[n-1]+1];
    Sort[FromDigits/@Join@@Table[Select[normseqs[n]-1,First[#]>0&&polyQ[#]&],{n,8}]]

A305715 Irregular triangle whose rows are all finite sequences of positive integers that are polydivisible and strictly pandigital.

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 3, 2, 1, 1, 2, 3, 6, 5, 4, 3, 2, 1, 6, 5, 4, 3, 8, 1, 6, 5, 4, 7, 2, 3, 8, 1, 6, 5, 4, 7, 2, 9, 3, 8, 1, 6, 5, 4, 7, 2, 9, 10
Offset: 1

Views

Author

Gus Wiseman, Jun 08 2018

Keywords

Comments

A positive integer sequence q of length k is strictly pandigital if it is a permutation of {1,2,...,k}. It is polydivisible if Sum_{i = 1...m} 10^(m - i) * q_i is a multiple of m for all 1 <= m <= k.

Examples

			Triangle is:
  {1}
  {1,2}
  {1,2,3}
  {3,2,1}
  {1,2,3,6,5,4}
  {3,2,1,6,5,4}
  {3,8,1,6,5,4,7,2}
  {3,8,1,6,5,4,7,2,9}
  {3,8,1,6,5,4,7,2,9,10}
		

References

  • Matt Parker, Things to make and do in the fourth dimension, 2015, pages 7-9.

Crossrefs

Programs

  • Mathematica
    polyQ[q_]:=And@@Table[Divisible[FromDigits[Take[q,k]],k],{k,Length[q]}];
    Flatten[Table[Select[Permutations[Range[n]],polyQ],{n,8}]]

A352991 Concatenation of all the distinct permutations of the first 1, 2, 3, ... (strictly) positive integers, arranged in ascending numerical order.

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

Views

Author

Marco Ripà, Apr 16 2022

Keywords

Comments

This sequence differs from A030299 starting from a(409114) = 10123456789. All the permutations are listed once and only once (e.g., the concatenation of the permutations of the elements of the set {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11} originates the number 1112345678910 which is a unique element of this sequence and appears only once, since 1_11_23456789 = 11_1_23456789 = 1112345678910).
A001292 is a subsequence of the present sequence. An open problem, published by Kenichiro Kashihara in 1996 (see References, p. 25, #30, Problem 2), is to find how many terms of A001292 (which is a subsequence of A030299) are powers of integers; Kashihara conjectured that there are none (even if, clearly, A001292(1) = 1 should be disregarded in order to keep the conjecture alive). Currently, only the terms up to the prime a(409120) = 10123457689 have been directly checked by the author of this sequence and no nontrivial perfect power has been found. On the other hand, many (maybe infinitely many) terms of the present sequence are nontrivial powers of integers (e.g., A352329(2) to A352329(36) are squares of integers and belong to this sequence).
Although A181129 is a subsequence of the present one, so that A181129(1) = a(19) = 2341, a(14) is the smallest prime in this sequence.
The number of digits of a(n) comes from A058183. There are exactly k! (Cf. A000142) terms having A058183(k) digits. - David A. Corneth, Apr 17 2022

Examples

			a(3) = 21, since the number of permutations of {1, 2} is 2! = 2 and the concatenation 1_2 is smaller than 2_1 (while {1} originates only a(1) = 1, so that a(2) = 21).
		

References

  • Kenichiro Kashihara, Comments and Topics on Smarandache Notions and Problems, 25. Erhus University Press, Arizona, 1996. ISBN: 1-879585-55-3.

Crossrefs

Programs

  • Python
    from itertools import count, islice, permutations
    def agen(): # generator of terms
        for k in count(1):
            s = (int("".join(map(str, p))) for p in permutations(range(1, k+1)))
            yield from sorted(set(s))
    print(list(islice(agen(), 42))) # Michael S. Branicky, Apr 16 2022

A199168 Numbers whose digits are a permutation of (0,...,m) for some m.

Original entry on oeis.org

0, 10, 102, 120, 201, 210, 1023, 1032, 1203, 1230, 1302, 1320, 2013, 2031, 2103, 2130, 2301, 2310, 3012, 3021, 3102, 3120, 3201, 3210, 10234, 10243, 10324, 10342, 10423, 10432, 12034, 12043, 12304, 12340, 12403, 12430, 13024, 13042, 13204, 13240, 13402, 13420
Offset: 1

Views

Author

M. F. Hasler, Jan 08 2013

Keywords

Comments

2013 is the fourth odd term in this sequence: Up to and including the 5 digit terms, odd terms must end in 1 or 3.
Due to the fact that 0 is not allowed as initial digit, this sequence is quite different from A030299, the analog with digits (1,...,m) instead of (0,...,m).

Crossrefs

Cf. A187796 (subset of primes), A203569 (also a subset), A030299 (permutations of 1..m) and references therein.
Pandigital numbers A050278 are also a subset.
Cf. A297062.

Programs

  • Maple
    f:= proc(n) map(L -> add(L[i]*10^(n-i),i=1..n), select(L -> L[1] <> 0, combinat:-permute([$0..n-1]))) end proc:
    f(1):= [0]:
    seq(op(f(n)),n=1..5); # Robert Israel, Jan 09 2025
  • PARI
    n_digit_terms(n)={my(a=[],p=vector(n,i,10^(n-i))~);for(i=(n-1)!,n!-(n>1),a=concat(a,numtoperm(n,i)%n*p));vecsort(a)} \\ - M. F. Hasler, Jan 08 2013
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