A174662 Partial sums of A003149.

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

Offset

0,2

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.

Links

Table of n, a(n) for n=0..20.

Formula

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

Example

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

Crossrefs

Cf. A003149, A046825, A046878, A046879, A052186, A006932, A145878.

Sequence in context: A125655 A134165 A071016 * A002104 A102919 A363212

Adjacent sequences: A174659 A174660 A174661 * A174663 A174664 A174665

Keyword

nonn,easy

Author

Jonathan Vos Post, Nov 30 2010

Extensions

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

Status

approved