111035domain: NAppears in sequencesIndices of square numbers which are also heptagonal.at n=5A04619640*n^2 + 9 is a square.at n=11A075873a(n) = Sum_{k=0..floor(2*n/5)} (k+1) * binomial(k,2*n-5*k).at n=42A392268a(n) = Sum_{k=0..floor(3*n/5)} (k+1) * binomial(k,3*n-5*k).at n=28A392311