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.

Previous Showing 21-23 of 23 results.

A128152 Numerator of Sum_{k=0..n} 1/binomial(n,k)^4.

Original entry on oeis.org

1, 2, 33, 164, 20825, 10017, 25940593, 34743416, 3074035689, 672229195, 13443874324243, 431453199593, 53678600587865227, 33768054132971557, 813464644344955, 748569723383876272, 67454811525665973337193
Offset: 0

Views

Author

Alexander Adamchuk, May 10 2007

Keywords

Comments

p^k divides a(p^k-1) for prime p and integer k > 0. p divides a(p-2) for prime p > 5.

Crossrefs

Cf. A046825 (numerator of Sum_{k=0..n} 1/C(n, k)).
Cf. A100516 (numerator of Sum_{k=0..n} 1/C(n, k)^2).
Cf. A100518 (numerator of Sum_{k=0..n} 1/C(n, k)^3).

Programs

  • Mathematica
    Table[ Numerator[ Sum[ 1 / Binomial[n,k]^4, {k,0,n} ] ], {n,0,50} ]

Formula

a(n) = numerator(Sum_{k=0..n} 1/binomial(n,k)^4).

A174662 Partial sums of A003149.

Original entry on oeis.org

1, 3, 8, 24, 88, 400, 2212, 14500, 110116, 951076, 9205156, 98646436, 1159016356, 14808626596, 204358994596, 3028436306596, 47955883346596, 807990334802596, 14430691329362596, 272302801683794596, 5412861968581970596
Offset: 0

Views

Author

Jonathan Vos Post, Nov 30 2010

Keywords

Comments

Total resistance of a circuit whose n-th component is between opposite corners of an n-dimensional hypercube of unit resistors, multiplied by n!. The only prime in the sequence is 3. The subsequence of squares begins 1, 400, 9205156 = 2^2 * 37^2 * 41^2.

Examples

			a(5) = 1 + 2 + 5 + 16 + 64 + 312 = 400 = 2^4 * 5^2.
		

Crossrefs

Formula

a(n) = Sum_{i=0..n} Sum_{k=0..i} k!*(i-k)!.

Extensions

Offset set to 0 by Alois P. Heinz, Jun 28 2017

A177737 Partial sums of A046878.

Original entry on oeis.org

0, 1, 2, 7, 9, 17, 30, 181, 213, 296, 369, 1802, 2449, 17790, 46001, 56448, 57664, 77009, 95190, 746935, 2289093, 3753007, 6539606, 128829523, 158059067, 298060788, 432415361, 1207300530, 1953285227, 43665199740, 124195273633
Offset: 0

Views

Author

Jonathan Vos Post, May 12 2010

Keywords

Crossrefs

Formula

a(n) = Sum_{i=0..n} A046878(i).
Previous Showing 21-23 of 23 results.