A216703 - OEIS

%I #16 Jan 03 2021 12:31:16

%S 1,42,1911,89180,4213755,200574738,9594158301,460519598448,

%T 22162505675310,1068725273676060,51619430718553698,

%U 2496503376570051576,120872371815599997138,5857661095679076784380,284096563140435224042430,13788153197749122873525936

%N a(n) = Product_{k=1..n} (49 - 7/k).

%C This sequence is generalizable: Product_{k=1..n} (q^2 - q/k) = (q^n/n!) * Product_{k=0..n-1} (q*k + q-1) = expansion of (1- x*q^2)^((1-q)/q).

%p seq(product(49-7/k, k=1.. n), n=0..20);

%p seq((7^n/n!)*product(7*k+6, k=0.. n-1), n=0..20);

%Y Cf. A004988, A049382, A004994, A216702.

%K nonn

%O 0,2

%A _Michel Lagneau_, Sep 16 2012