A173516 a(1)=1, a(n) = 3*n*a(n-1) + 1, n > 1.

1, 7, 64, 769, 11536, 207649, 4360630, 104655121, 2825688268, 84770648041, 2797431385354, 100707529872745, 3927593665037056, 164958933931556353, 7423152026920035886, 356311297292161722529, 18171876161900247848980

Offset: 1

Author

Gary Detlefs, Feb 20 2010

Keywords

• nonn
• easy

Comments

If s(n) is a sequence defined as s(0) = x, s(n) = 3n*s(n-1)+k then s(n) = 3^n*n!*x + a(n)*k, n > 0.

Crossrefs

Cf. A002627, A056541.

Formula

E.g.f.: (exp(x)-1) / (1-3*x). - Kevin Ryde, Apr 16 2024