OFFSET
1,1
COMMENTS
For further information, see A349736.
FORMULA
a(n) = (2/n) * binomial(n^2+4n+2,(n^2+3n-2)/2) = (2/n) * A349476(n) for n >= 1.
a(n) ~ c*2^(n^2+4*n)/n^2, where c = 8*sqrt(2/(Pi*e)). - Stefano Spezia, Nov 29 2021
EXAMPLE
For n = 1, row 7 of Pascal's triangle is 1, 7, 21, 35, 35, 21, 7, 1; C(7,1) = 7, C(7,2) = 21 and C(7,3) = 35 form an arithmetic progression with common difference = 14, hence a(3) = 14.
For n = 2, row 14 is 1, 14, 91, 364, 1001, 2002, 3003, 3432, 3003, 2002, 1001, 364, 91, 14, 1; C(14,4) = 1001 , C(14,5) = 2002 and C(14,6) = 3003 form an arithmetic progression with common difference = 1001, hence a(4) = 1001.
MAPLE
Sequence = seq((2/n)*binomial(n^2+4*n+2, (n^2+3*n-2)/2), n=1..16);
MATHEMATICA
nterms=15; Table[2/n*Binomial[n^2+4n+2, (n^2+3n-2)/2], {n, nterms}] (* Paolo Xausa, Nov 29 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Bernard Schott, Nov 28 2021
STATUS
approved