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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A181322 Square array A(n,k), n>=0, k>=0, read by antidiagonals: A(n,k) is the number of partitions of 2*n into powers of 2 less than or equal to 2^k.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 4, 4, 1, 1, 2, 4, 6, 5, 1, 1, 2, 4, 6, 9, 6, 1, 1, 2, 4, 6, 10, 12, 7, 1, 1, 2, 4, 6, 10, 14, 16, 8, 1, 1, 2, 4, 6, 10, 14, 20, 20, 9, 1, 1, 2, 4, 6, 10, 14, 20, 26, 25, 10, 1, 1, 2, 4, 6, 10, 14, 20, 26, 35, 30, 11, 1, 1, 2, 4, 6, 10, 14, 20, 26, 36, 44, 36, 12, 1, 1, 2, 4, 6, 10, 14, 20, 26, 36, 46, 56, 42, 13, 1
Offset: 0

Views

Author

Alois P. Heinz, Jan 26 2011

Keywords

Comments

Column sequences converge towards A000123.

Examples

			A(3,2) = 6, because there are 6 partitions of 2*3=6 into powers of 2 less than or equal to 2^2=4: [4,2], [4,1,1], [2,2,2], [2,2,1,1], [2,1,1,1,1], [1,1,1,1,1,1].
Square array A(n,k) begins:
  1,  1,  1,  1,  1,  1,  ...
  1,  2,  2,  2,  2,  2,  ...
  1,  3,  4,  4,  4,  4,  ...
  1,  4,  6,  6,  6,  6,  ...
  1,  5,  9, 10, 10, 10,  ...
  1,  6, 12, 14, 14, 14,  ...
		

Crossrefs

Columns k=0-5 give: A000012, A000027(n+1), A002620(n+2), A008804, A088932, A088954.
Main diagonal gives A000123.
Cf. A145515.
See A262553 for another version of this array.
See A072170 for a related array (having the same limiting column).

Programs

  • Maple
    b:= proc(n, j) local nn, r;
          if n<0 then 0
        elif j=0 then 1
        elif j=1 then n+1
        elif n b(n/2^(k-1), k):
    seq(seq(A(n, d-n), n=0..d), d=0..13);
  • Mathematica
    b[n_, j_] := b[n, j] = Module[{nn, r}, Which[n<0, 0, j == 0, 1, j == 1, n+1, nJean-François Alcover, Jan 15 2014, translated from Maple *)
  • PARI
    A181322(n,k,r=1)={if(nA181322(n-1,k,0)+A181322(2*n,k-1,0),n-=r=1+n\1,(r-k)*binomial(r,k)*sum(i=0,min(k-1,k+n), binomial(k,i)/(r-k+i)*A181322(k-i+n,k,0) *(-1)^i))} \\ From Maple. - M. F. Hasler, Feb 19 2019

Formula

G.f. of column k: 1/(1-x) * 1/Product_{j=0..k-1} (1 - x^(2^j)).
A(n,k) = Sum_{i=0..k} A089177(n,i).
For n < 2^k, T(n,k) = A000123(k). T(n,0) = 1, T(n,1) = n+1. - M. F. Hasler, Feb 19 2019

A262554 Triangle read by rows: coefficients in Bell's formula for number of ways of making change when coins have denominations which are powers of 2.

Original entry on oeis.org

1, 1, 1, 1, 3, 2, 1, 9, 16, 8, 1, 35, 130, 160, 64, 1, 201, 1424, 3272, 3072, 1024, 1, 1827, 23682, 91040, 151104, 114688, 32768, 1, 27337, 637328, 3872456, 10136576, 13165568, 8388608, 2097152, 1, 692003, 28867714, 268176288, 1041587776, 2061746176
Offset: 1

Views

Author

N. J. A. Sloane, Oct 09 2015

Keywords

Examples

			Triangle begins:
  1;
  1,    1;
  1,    3,     2;
  1,    9,    16,     8;
  1,   35,   130,   160,     64;
  1,  201,  1424,  3272,   3072,   1024;
  1, 1827, 23682, 91040, 151104, 114688, 32768;
  ...
		

Crossrefs

A002575 and A002576 are diagonals.

Extensions

More terms from Sean A. Irvine, Oct 19 2015
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