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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A194588 a(n) = A189912(n-1)-a(n-1) for n>0, a(0) = 1; extended Riordan numbers.

Original entry on oeis.org

1, 0, 2, 2, 8, 17, 49, 128, 356, 983, 2759, 7779, 22087, 63000, 180478, 518846, 1496236, 4326383, 12539335, 36419069, 105971473, 308866226, 901573732, 2635235789, 7712078755, 22594899002, 66266698424, 194531585078, 571561286576, 1680679630089, 4945738222801
Offset: 0

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Author

Peter Luschny, Aug 30 2011

Keywords

Crossrefs

Programs

  • Maple
    A189912 := n -> add(n!/((n-k)!*iquo(k,2)!^2 *(iquo(k,2)+1)),k=0..n):
    A194588 := n -> `if`(n=0,1,A189912(n-1)-A194588(n-1)):
  • Mathematica
    a[0] = 1; a[n_] := a[n] = Sum[(n-1)!/((n-k-1)!*Quotient[k, 2]!^2*(1 + Quotient[k, 2])), {k, 0, n-1}] - a[n-1]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Jul 30 2013 *)

Formula

a(n) = ((n+1) mod 2) + (1/2)*sum_{k=1..n}((-1)^k*binomial(n,k)*((k+1)/2)^(k mod 2)*(k+1)$+2*(-1)^n*(2*k)$/(k+1)), where n$ denotes the swinging factorial A056040(n).

A194590 a(n) = (-1)^n*(A056040(n+1)*A152271(n)-2^n)/2.

Original entry on oeis.org

0, 0, 1, -2, 7, -14, 38, -76, 187, -374, 874, -1748, 3958, -7916, 17548, -35096, 76627, -153254, 330818, -661636, 1415650, -2831300, 6015316, -12030632, 25413342, -50826684, 106853668, -213707336, 447472972, -894945944, 1867450648, -3734901296, 7770342787
Offset: 0

Views

Author

Peter Luschny, Aug 30 2011

Keywords

Comments

The binomial transform of a(n) are the complementary Riordan numbers A194589 (see link).

Crossrefs

Cf. A107373 (has offset 1).

Programs

  • Maple
    A056040 := n -> n!/iquo(n,2)!^2:
    A152271 := n -> `if`(n mod 2 = 0, 1, (n+1)/2):
    A194590 := n -> (-1)^n*(A056040(n+1)*A152271(n)-2^n)/2:
  • Mathematica
    sf[n_] := n!/Quotient[n, 2]!^2;
    a[n_] := (-1)^n (sf[n + 1] * If[EvenQ[n], 1, (n + 1)/2] - 2^n)/2;
    Table[a[n], {n, 0, 32}] (* Jean-François Alcover, Jun 26 2019 *)

Formula

a(n) = Sum_{k=0..n} (-1)^(n-k)*binomial(n,k)*cr(k), where cr(k) are the complementary Riordan numbers A194589.
Showing 1-2 of 2 results.