>>419 >>426

a_n = Σ(k=1,n+1) [kk/4]

生成関数は x/{(1+x)(1-x)^4}

1, 3, 7, 13, 22, 34, 50, 70, 95, 125, 161, 203, 252, 308, 372, 444, 525, 615, 715, …

http://oeis.org/A173196