A368466 a(n) = Sum_{k=0..n} 2^k * k^n.

1, 2, 18, 250, 4810, 118458, 3557610, 126109562, 5153959338, 238596116794, 12340467941098, 705262375055610, 44135963944338474, 3001795007526424250, 220466095716711140202, 17389850740043552754298, 1466156761178169939270826, 131580021359494993268692026

Offset: 0

Author

Seiichi Manyama, Dec 25 2023

Keywords

• nonn
• easy

Crossrefs

Main diagonal of A368479.

Cf. A031971, A120485, A349963.

Programs

PARI

a(n) = sum(k=0, n, 2^k*k^n);

Formula

a(n) ~ 2^n * n^n / (1 - exp(-1)/2). - Vaclav Kotesovec, Dec 26 2023