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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A294212 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where column k is the expansion of e.g.f.: exp(Product_{j=1..n} 1/(1-x^j) - 1).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 3, 0, 1, 1, 5, 13, 0, 1, 1, 5, 25, 73, 0, 1, 1, 5, 31, 193, 501, 0, 1, 1, 5, 31, 241, 1601, 4051, 0, 1, 1, 5, 31, 265, 2261, 16741, 37633, 0, 1, 1, 5, 31, 265, 2501, 25501, 190345, 394353, 0, 1, 1, 5, 31, 265, 2621, 29461, 319915, 2509025
Offset: 0

Views

Author

Seiichi Manyama, Oct 25 2017

Keywords

Examples

			Square array B(j,k) begins:
   1,   1,    1,    1,    1, ...
   0,   1,    1,    1,    1, ...
   0,   1,    2,    2,    2, ...
   0,   1,    2,    3,    3, ...
   0,   1,    3,    4,    5, ...
   0,   1,    3,    5,    6, ...
Square array A(n,k) begins:
   1,   1,    1,    1,    1, ...
   0,   1,    1,    1,    1, ...
   0,   3,    5,    5,    5, ...
   0,  13,   25,   31,   31, ...
   0,  73,  193,  241,  265, ...
   0, 501, 1601, 2261, 2501, ...
		

Crossrefs

Columns k=0..5 give A000007, A000262, A294213, A294214, A294215, A294216.
Rows n=0 gives A000012.
Main diagonal gives A058892.

Formula

B(j,k) is the coefficient of Product_{i=1..k} 1/(1-x^i).
A(0,k) = 1 and A(n,k) = (n-1)! * Sum_{j=1..n} j*B(j,k)*A(n-j,k)/(n-j)! for n > 0.

A294253 E.g.f.: exp((1+x)*(1+x^2)*(1+x^3)*(1+x^4)*(1+x^5) - 1).

Original entry on oeis.org

1, 1, 3, 19, 121, 1041, 9931, 106723, 1313649, 17830081, 265652371, 4259421651, 74011854313, 1374298028689, 27230459440731, 573414615381091, 12723857450638561, 297915550887491073, 7328943525355675939, 188820746254730967571, 5086439179764958688601
Offset: 0

Views

Author

Seiichi Manyama, Oct 26 2017

Keywords

Crossrefs

Column k=5 of A294250.
Cf. A294216.

Programs

  • Mathematica
    With[{nn=20},CoefficientList[Series[Exp[Times@@(1+x^Range[5])-1],{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Mar 16 2023 *)
  • PARI
    N=66; x='x+O('x^N); Vec(serlaplace(exp((1+x)*(1+x^2)*(1+x^3)*(1+x^4)*(1+x^5)-1)))

Formula

Recurrence: a(n) = a(n-1) + 2*(n-1)*a(n-2) + 6*(n-2)*(n-1)*a(n-3) + 8*(n-3)*(n-2)*(n-1)*a(n-4) + 15*(n-4)*(n-3)*(n-2)*(n-1)*a(n-5) + 18*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*a(n-6) + 21*(n-6)*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*a(n-7) + 24*(n-7)*(n-6)*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*a(n-8) + 27*(n-8)*(n-7)*(n-6)*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*a(n-9) + 30*(n-9)*(n-8)*(n-7)*(n-6)*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*a(n - 10) + 22*(n - 10)*(n-9)*(n-8)*(n-7)*(n-6)*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*a(n - 11) + 24*(n - 11)*(n - 10)*(n-9)*(n-8)*(n-7)*(n-6)*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*a(n - 12) + 13*(n - 12)*(n - 11)*(n - 10)*(n-9)*(n-8)*(n-7)*(n-6)*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*a(n - 13) + 14*(n - 13)*(n - 12)*(n - 11)*(n - 10)*(n-9)*(n-8)*(n-7)*(n-6)*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*a(n - 14) + 15*(n - 14)*(n - 13)*(n - 12)*(n - 11)*(n - 10)*(n-9)*(n-8)*(n-7)*(n-6)*(n-5)*(n-4)*(n-3)*(n-2)*(n-1)*a(n - 15). - Vaclav Kotesovec, Dec 02 2021
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