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.
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
KEYWORD
nonn,easy
AUTHOR
Jonathan Vos Post, Nov 30 2010
EXTENSIONS
Offset set to 0 by Alois P. Heinz, Jun 28 2017
STATUS
approved