A276940 a(1) = 2; for n > 1, a(n) = (n-2)! * n^3.

2, 8, 27, 128, 750, 5184, 41160, 368640, 3674160, 40320000, 482993280, 6270566400, 87697209600, 1314380390400, 21016195200000, 357082280755200, 6424604169984000, 122021710626816000, 2439660069310464000, 51218989645824000000, 1126555274886193152000, 25905540583064862720000, 621623493403188756480000, 15538186060797648568320000

Offset

1,1

Comments

In factorial base representation (A007623) the terms are written as: 10, 110, 1011, 10110, 101100, 1011000, 10110000, ... From a(3) = 27 = "1011" onward each term begins always with "1011", followed by n-3 zeros. - Antti Karttunen, Sep 24 2016

Links

Table of n, a(n) for n=1..24.

Index entries for sequences related to factorial base representation

Formula

a(1) = 2; for n > 1, a(n) = (n-2)! * n^3.

a(n) = n * A054119(n).

For n >= 3, a(n) = (n+1)! + (n-1)! + (n-2)!.

Mathematica

Join[{2}, Table[(n-2)! n^3, {n, 2, 30}]] (* Harvey P. Dale, Apr 14 2017 *)

Prog

(Scheme, two alternatives)
(define (A276940 n) (if (= 1 n) 2 (* n n n (A000142 (- n 2)))))
(define (A276940 n) (cond ((= 1 n) 2) ((= 2 n) 8) (else (+ (A000142 (+ 1 n)) (A000142 (- n 1)) (A000142 (- n 2))))))

Crossrefs

Cf. A000142, A000578, A054119.

Row 20 of A276955 (from a(3) = 27 onward).

Sequence in context: A150711 A150712 A150713 * A287204 A299640 A197932

Adjacent sequences: A276937 A276938 A276939 * A276941 A276942 A276943

Keyword

nonn,base

Author

Antti Karttunen, Sep 24 2016

Status

approved