A281596 a(n) = ((n-2)^n - 2*(n-1)^n + n^n)/2.

0, 0, 1, 6, 55, 660, 9751, 170898, 3463615, 79669320, 2050086511, 58346365110, 1819621847407, 61705703989020, 2260586259354151, 88971796139662842, 3743940350046570751, 167735288431662235920, 7971302827015366403551, 400510700317394780627934, 21212944650652080893863087

Offset

0,4

Links

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

Formula

a(n) ~ n^n*(1/2+(1/2-1/n)*e^(-2)+(1/(2*n)-1)*e^(-1)).

Maple

a := n -> ((n-2)^n-2*(n-1)^n+n^n)/2:
seq(a(n), n=0..21);

Crossrefs

Cf. A000312, A045531, A281595.

Sequence in context: A006200 A243691 A151345 * A095652 A132689 A323876

Adjacent sequences: A281593 A281594 A281595 * A281597 A281598 A281599

Keyword

nonn

Author

Peter Luschny, Jan 26 2017

Status

approved