A101634 Subtract 1, multiply by 1, subtract 2, multiply by 2, etc.

6, 5, 6, 9, 20, 75, 414, 2849, 22728, 204471, 2044610, 22490589, 269886924, 3508529843, 49119417606, 736791263865, 11788660221584, 200407223766639, 3607330027799178, 68539270528184021, 1370785410563680020

Offset

1,1

Comments

Inspired by A019460. a(1) = 6 is the least integer producing all nonnegative terms.

Links

Table of n, a(n) for n=1..21.

Formula

Recurrence: a(1) = 6; a(n+1) = n*a(n) - n^2. [Edited by Georg Fischer, Dec 28 2021]

Mathematica

a=6; bb={a}; Do[b=i(a-i); a=b; bb={bb, a}, {i, 20}]; Flatten[bb]

Crossrefs

Cf. A019460.

Sequence in context: A335263 A126689 A243093 * A071176 A243091 A195786

Adjacent sequences: A101631 A101632 A101633 * A101635 A101636 A101637

Keyword

easy,nonn

Author

Zak Seidov, Jan 26 2005

Status

approved