A321666 Number of arrangements of n 1's, n 2's, ..., n n's avoiding equal consecutive terms and introduced in ascending order.

1, 1, 1, 29, 94376, 66218360625, 16985819072511102549, 2421032324142610480402567434373, 271259741131895052775392614041761701799270286, 32119646666355552112999645991677870426882424139287301894021793

Offset

0,4

Links

Seiichi Manyama, Table of n, a(n) for n = 0..27

Formula

a(n) = A321634(n)/n!.

a(n) ~ exp(5/12) * n^((n-1)*(2*n-1)/2) / (2*Pi)^(n/2). - Vaclav Kotesovec, Nov 24 2018

Prog

(PARI) {a(n) = sum(i=n, n^2, i!*polcoef(sum(j=1, n, (-1)^(n-j)*binomial(n-1, j-1)*x^j/j!)^n, i))/n!} \\ Seiichi Manyama, May 27 2019

Crossrefs

Cf. A190826, A190830, A190833, A190835, A190836, A190837, A278990, A321634.

Sequence in context: A159437 A343451 A185822 * A139775 A303734 A087528

Adjacent sequences: A321663 A321664 A321665 * A321667 A321668 A321669

Keyword

nonn

Author

Seiichi Manyama, Nov 16 2018

Status

approved