OFFSET
0,10
COMMENTS
LINKS
Antti Karttunen, Table of n, a(n) for n = 0..6561
FORMULA
EXAMPLE
Row 9 of Pascal's triangle is {1, 9, 36, 84, 126, 126, 84, 36, 9, 1}. The terms 9, 36, and 126 are the only multiples of nine, and each of them occurs two times on that row, thus a(9) = 2*3 = 6.
Row 10 of Pascal's triangle is {1, 10, 45, 120, 210, 252, 210, 120, 45, 10, 1}. The terms 45 (= 9*5) and 252 (= 9*28) are the only multiples of nine, and the former occurs twice, while the latter is alone at the center, thus a(10) = 2+1 = 3.
MATHEMATICA
Total/@Table[If[Mod[Binomial[n, k], 9]==0, 1, 0], {n, 0, 80}, {k, 0, n}] (* Harvey P. Dale, Feb 12 2020 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 04 2014
STATUS
approved