A102428 Central column of triangle A102427.

1, 3, 6, 28, 55, 286, 560, 3060, 5985, 33649, 65780, 376740, 736281, 4272048, 8347680, 48903492, 95548245, 563921995, 1101716330, 6540715896, 12777711870, 76223753060, 148902215280, 891794789340, 1742058970275, 10468434365991, 20448884000160, 123234279768160

Offset

0,2

Links

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

Formula

a(n) = binomial(floor((5*n+2)/2), floor((n+1)/2)). - David Wasserman, Apr 04 2008

a(n) ~ c * 5^(5*n/2+1) / (2^(4*n+3) * sqrt(Pi*n)), where c = 4 if n is odd, and c = sqrt(5) if n is even. - Amiram Eldar, Dec 06 2025

Mathematica

Table[Binomial[Floor[(5n+2)/2], Floor[(n+1)/2]], {n, 0, 30}] (* Harvey P. Dale, Mar 13 2015 *)

Crossrefs

Cf. A011973, A102426, A102427, A102429.

Sequence in context: A076711 A075088 A391393 * A128056 A068808 A068133

Adjacent sequences: A102425 A102426 A102427 * A102429 A102430 A102431

Keyword

nonn,easy

Author

Russell Walsmith, Jan 11 2005

Extensions

More terms from David Wasserman, Apr 04 2008

Status

approved