564929domain: NAppears in sequencesNumerator of Sum_{k=0..n} binomial(n,k)/2^(k*(k-1)/2).at n=6A079491a(n) = Sum_{k=0..n} binomial(k, 7*(n-k)).at n=24A306721Number of compositions of 8*n into parts 7 and 8.at n=21A373913a(n) = Sum_{k=0..floor(4*n/7)} binomial(k,4*n-7*k).at n=42A392355