A001345 a(n) = Sum_{k = 0..3} (n+k)! C(3,k). (Formerly M4352 N1822)

7, 16, 49, 212, 1158, 7584, 57720, 499680, 4843440, 51932160, 610001280, 7787404800, 107336275200, 1588369305600, 25113574886400, 422465999155200, 7533512034048000, 141940206600192000, 2817400117948416000, 58760985871171584000, 1284693905417674752000

Offset

-1,1

References

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

T. D. Noe, Table of n, a(n) for n = -1..100

E. Biondi, L. Divieti, G. Guardabassi, Counting paths, circuits, chains and cycles in graphs: A unified approach, Canad. J. Math. 22 1970 22-35.

Mathematica

Join[{7}, Table[Sum[(n + k)! Binomial[3, k], {k, 0, 3}], {n, 0, 20}]] (* T. D. Noe, Jun 28 2012 *)

Prog

(PARI) a(n) = if (n == -1, 7, sum(k=0, 3, (n+k)!*binomial(3, k))); \\ Michel Marcus, Jun 30 2017

Crossrefs

Cf. A001346, A001347.

Sequence in context: A173661 A152530 A065099 * A225128 A056613 A318413

Adjacent sequences: A001342 A001343 A001344 * A001346 A001347 A001348

Keyword

easy,nonn

Author

N. J. A. Sloane

Extensions

More terms from Sean A. Irvine, Jun 19 2012

Status

approved