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.

Showing 1-7 of 7 results.

A214676 A(n,k) is n represented in bijective base-k numeration; square array A(n,k), n>=1, k>=1, read by antidiagonals.

Original entry on oeis.org

1, 1, 11, 1, 2, 111, 1, 2, 11, 1111, 1, 2, 3, 12, 11111, 1, 2, 3, 11, 21, 111111, 1, 2, 3, 4, 12, 22, 1111111, 1, 2, 3, 4, 11, 13, 111, 11111111, 1, 2, 3, 4, 5, 12, 21, 112, 111111111, 1, 2, 3, 4, 5, 11, 13, 22, 121, 1111111111
Offset: 1

Views

Author

Alois P. Heinz, Jul 25 2012

Keywords

Comments

The digit set for bijective base-k numeration is {1, 2, ..., k}.

Examples

			Square array A(n,k) begins:
:         1,   1,  1,  1,  1,  1,  1,  1, ...
:        11,   2,  2,  2,  2,  2,  2,  2, ...
:       111,  11,  3,  3,  3,  3,  3,  3, ...
:      1111,  12, 11,  4,  4,  4,  4,  4, ...
:     11111,  21, 12, 11,  5,  5,  5,  5, ...
:    111111,  22, 13, 12, 11,  6,  6,  6, ...
:   1111111, 111, 21, 13, 12, 11,  7,  7, ...
:  11111111, 112, 22, 14, 13, 12, 11,  8, ...
		

Crossrefs

A(n+1,n) gives A010850.

Programs

  • Maple
    A:= proc(n, b) local d, l, m; m:= n; l:= NULL;
          while m>0 do  d:= irem(m, b, 'm');
            if d=0 then d:=b; m:=m-1 fi;
            l:= d, l
          od; parse(cat(l))
        end:
    seq(seq(A(n, 1+d-n), n=1..d), d=1..12);
  • Mathematica
    A[n_, b_] := Module[{d, l, m}, m = n; l = Nothing; While[m > 0, {m, d} = QuotientRemainder[m, b]; If[d == 0, d = b; m--]; l = {d, l}]; FromDigits @ Flatten @ l];
    Table[A[n, d-n+1], {d, 1, 12}, {n, 1, d}] // Flatten (* Jean-François Alcover, May 28 2019, from Maple *)

A023010 Number of partitions of n into parts of 11 kinds.

Original entry on oeis.org

1, 11, 77, 418, 1925, 7854, 29183, 100529, 325193, 997150, 2919411, 8207563, 22259237, 58454165, 149104450, 370410700, 898202998, 2130141651, 4949034937, 11281187225, 25262712629, 55641782779, 120661583781, 257862888360, 543532730675, 1130864017283
Offset: 0

Views

Author

Keywords

Comments

a(n) is Euler transform of A010850. - Alois P. Heinz, Oct 17 2008

Crossrefs

Cf. 11th column of A144064. - Alois P. Heinz, Oct 17 2008

Programs

  • Maple
    with(numtheory): a:= proc(n) option remember; `if`(n=0, 1, add(add(d*11, d=divisors(j)) *a(n-j), j=1..n)/n) end: seq(a(n), n=0..40); # Alois P. Heinz, Oct 17 2008
  • Mathematica
    nmax=50; CoefficientList[Series[Product[1/(1-x^k)^11,{k,1,nmax}],{x,0,nmax}],x] (* Vaclav Kotesovec, Feb 28 2015 *)
    CoefficientList[Series[1/QPochhammer[x]^11, {x, 0, 30}], x] (* Indranil Ghosh, Mar 27 2017 *)
  • PARI
    Vec(1/eta(x)^11 + O(x^30)) \\ Indranil Ghosh, Mar 27 2017

Formula

G.f.: Product_{m>=1} 1/(1-x^m)^11.
a(n) ~ 1331 * exp(Pi * sqrt(22*n/3)) / (2^(19/2) * 27 * n^(7/2)). - Vaclav Kotesovec, Feb 28 2015
a(0) = 1, a(n) = (11/n)*Sum_{k=1..n} A000203(k)*a(n-k) for n > 0. - Seiichi Manyama, Mar 27 2017
G.f.: exp(11*Sum_{k>=1} x^k/(k*(1 - x^k))). - Ilya Gutkovskiy, Feb 06 2018

A156194 Period 12: 1,2,7,1,7,2,1,1,4,2,4,1 repeated.

Original entry on oeis.org

1, 2, 7, 1, 7, 2, 1, 1, 4, 2, 4, 1, 1, 2, 7, 1, 7, 2, 1, 1, 4, 2, 4, 1, 1, 2, 7, 1, 7, 2, 1, 1, 4, 2, 4, 1, 1, 2, 7, 1, 7, 2, 1, 1, 4, 2, 4, 1, 1, 2, 7, 1, 7, 2, 1, 1, 4, 2, 4, 1, 1, 2, 7, 1, 7, 2, 1, 1, 4, 2, 4, 1, 1, 2, 7, 1, 7, 2, 1, 1, 4, 2, 4, 1
Offset: 0

Views

Author

Paul Curtz, Feb 05 2009

Keywords

Comments

Also the decimal expansion of 42390704747/333333333333. - R. J. Mathar, Feb 23 2009

Programs

  • Mathematica
    PadRight[{},144,{1,2,7,1,7,2,1,1,4,2,4,1}] (* Harvey P. Dale, Mar 06 2012 *)

Formula

Palindromic properties: a(12k+i) = a(12k+6-i), i=0..3. a(12k+7+i) = a(12k+11-i), i=0..2, and similarly for successive differences.
a(n) = A156095(n) mod 9.
a(n) = A156094(n+6) mod 9.
a(4n) + a(4n+1) + a(4n+2) + a(4n+3) = A010850(n).
G.f.: (1+2*x+7*x^2+x^3+7*x^4+2*x^5+x^6+x^7+4*x^8+2*x^9+4*x^10+x^11)/((1-x)*(1+x+x^2)*(1+x)*(1-x+x^2)*(1+x^2)*(x^4-x^2+1)). - R. J. Mathar, Feb 23 2009

Extensions

Edited by R. J. Mathar, Feb 23 2009
More terms from Jinyuan Wang, Feb 26 2020

A299781 Triangle read by rows: T(n,m) = number of k-uniform tilings having m different arrangements of polygons about their vertices, for k = 1..n, with 1 <= m <= n.

Original entry on oeis.org

11, 11, 20, 11, 42, 39, 11, 75, 124, 33, 11, 149, 273, 127, 15, 11, 249, 557, 314, 107, 10, 11
Offset: 1

Views

Author

Omar E. Pol, Mar 30 2018

Keywords

Comments

Column m lists the partial sums of the m-th column of triangle A299780.

Examples

			Triangle begins:
  11;
  11,  20;
  11,  42,  39;
  11,  75, 124,  33;
  11, 149, 273, 127,  15;
  11, 249, 557, 314, 107, 10;
...
		

Crossrefs

Column 1 gives A010850.
Leading diagonal is A068600.
Row sums give A299782.

A368782 Comma transform of A366487.

Original entry on oeis.org

12, 35, 94, 15, 16, 28, 31, 34, 37, 41, 45, 55, 55, 55, 55, 61, 67, 74, 71, 89, 98, 97, 18, 19, 11, 11, 12, 13, 14, 15, 16, 17, 18, 19, 11, 11, 12, 13, 14, 15, 16, 17, 18, 22, 22, 24, 26, 28, 22, 22, 24, 26, 28, 22, 22, 24, 26, 28, 22, 22, 24, 26, 28, 22, 22
Offset: 1

Views

Author

Michael S. Branicky, Jan 05 2024

Keywords

Comments

See A367360 for further information.
Let the comma sequence A121805 be known as S or C0.
A366487, the first differences of A121805, is the same as the comma transform of A121805; call it C1.
This sequence is C2 = C(C(S)), the comma transform C iterated twice.
C4 = C2, C5 = C2, ... once the first term (and the last term if the sequence is finite) are removed from the lower iterates of C.
Theorem: C^{i+2}(S) = C^i(S) for i>=2 in general and for i>=0 when all terms of S have two digits and no least significant digit is zero. See link for proof.
Remark. The lexicographically earliest sequence S with C(S) = S is A010850, all 11's.
The sequence contains 2137451 terms, with a(2137451) = 96. The next term does not exist.

Crossrefs

Programs

  • Python
    from itertools import islice, pairwise
    def S(): # generator of comma sequence
        an = 1
        while True:
            yield an
            an += 10*(an%10)
            children = [an+y for y in range(1, 10) if str(an+y)[0] == str(y)]
            if not children: break
            an = children[0]
    def C(g): # generator of comma transform of sequence passed as a generator
        yield from (10*(t%10) + int(str(u)[0]) for t, u in pairwise(g))
    def agen(): return C(C(S()))
    print(list(islice(agen(), 70))) # Michael S. Branicky, Jan 05 2024

A267319 Continued fraction expansion of phi^8, where phi = (1 + sqrt(5))/2.

Original entry on oeis.org

46, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1, 45, 1
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 13 2016

Keywords

Comments

More generally, the ordinary generating function for the continued fraction expansion of phi^(2*k + 1), where phi = (1 + sqrt(5))/2, k = 1, 2, 3,... is floor(phi^(2*k + 1))/(1 - x), and for the continued fraction expansion of phi^(2*k) is (floor(phi^(2*k)) + x - x^2)/(1 - x^2).

Examples

			phi^8 = (47 + 21*sqrt(5))/2 = 46 + 1/(1 + 1/(45 + 1/(1 + 1/(45 + 1/(1 + 1/(45 + 1/...)))))).
		

Crossrefs

Cf. A001622.
Cf. continued fraction expansion of phi^k: A000012 (k = 1), A054977 (k = 2), A010709 (k = 3), A176260 (k = 4, for n>0), A010850 (k = 5), A040071 (k = 6, for n>0), A010868 (k = 7), this sequence (k = 8).

Programs

  • Magma
    [46] cat &cat [[1, 45]^^50]; // Vincenzo Librandi, Jan 13 2016
  • Mathematica
    ContinuedFraction[(47 + 21 Sqrt[5])/2, 82]

Formula

G.f.: (46 + x - x^2)/(1 - x^2).
a(n) = 23 + 22*(-1)^n for n>0. - Bruno Berselli, Jan 18 2016

A267615 a(n) = 2^n + 11.

Original entry on oeis.org

12, 13, 15, 19, 27, 43, 75, 139, 267, 523, 1035, 2059, 4107, 8203, 16395, 32779, 65547, 131083, 262155, 524299, 1048587, 2097163, 4194315, 8388619, 16777227, 33554443, 67108875, 134217739, 268435467, 536870923, 1073741835, 2147483659, 4294967307, 8589934603, 17179869195, 34359738379
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 18 2016

Keywords

Comments

Recurrence relation b(n) = 3*b(n - 1) - 2*b(n - 2) for n>1, b(0) = k, b(1) = k + 1, gives the closed form b(n) = 2^n + k - 1.

Crossrefs

Cf. sequences with closed form 2^n + k - 1: A168616 (k=-4), A028399 (k=-3), A036563 (k=-2), A000918 (k=-1), A000225 (k=0), A000079 (k=1), A000051 (k=2), A052548 (k=3), A062709 (k=4), A140504 (k=5), A168614 (k=6), A153972 (k=7), A168415 (k=8), A242475 (k=9), A188165 (k=10), A246139 (k=11), this sequence (k=12).
Cf. A156940.

Programs

  • Magma
    [2^n+11: n in [0..30]]; // Vincenzo Librandi, Jan 19 2016
  • Mathematica
    Table[2^n + 11, {n, 0, 35}]
    LinearRecurrence[{3, -2}, {12, 13}, 40] (* Vincenzo Librandi, Jan 19 2016 *)
  • PARI
    a(n) = 2^n + 11; \\ Altug Alkan, Jan 18 2016
    

Formula

G.f.: (12 - 23*x)/(1 - 3*x + 2*x^2).
a(n) = 3*a(n - 1) - 2*a(n - 2) for n>1, a(0)=12, a(1)=13.
a(n) = A000079(n) + A010850(n).
Sum_{n>=0} 1/a(n) = 0.367971714327125...
Lim_{n->oo} a(n + 1)/a(n) = 2.
E.g.f.: exp(2*x) + 11*exp(x). - Elmo R. Oliveira, Nov 08 2023
Showing 1-7 of 7 results.