A011927 [ n(n-1)(n-2)(n-3)/17 ].

0, 0, 0, 0, 1, 7, 21, 49, 98, 177, 296, 465, 698, 1009, 1413, 1927, 2569, 3360, 4320, 5472, 6840, 8449, 10327, 12501, 15001, 17858, 21105, 24776, 28905, 33530, 38689, 44421, 50767, 57769, 65472, 73920

Offset

0,6

Links

Table of n, a(n) for n=0..35.

Index entries for linear recurrences with constant coefficients, signature (4, -6, 4, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -4, 6, -4, 1).

Formula

From Chai Wah Wu, Aug 02 2020: (Start)

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) + a(n-17) - 4*a(n-18) + 6*a(n-19) - 4*a(n-20) + a(n-21) for n > 20.

G.f.: x^4*(-x^16 - 3*x^15 + x^14 - 3*x^13 - x^12 - 2*x^11 - x^10 - 4*x^8 - x^6 - 2*x^5 - x^4 - 3*x^3 + x^2 - 3*x - 1)/(x^21 - 4*x^20 + 6*x^19 - 4*x^18 + x^17 - x^4 + 4*x^3 - 6*x^2 + 4*x - 1). (End)

Prog

(PARI) a(n)=n*(n-1)*(n-2)*(n-3)\17 \\ Charles R Greathouse IV, Oct 18 2022

Crossrefs

Sequence in context: A146629 A195965 A137182 * A163723 A146669 A146637

Adjacent sequences: A011924 A011925 A011926 * A011928 A011929 A011930

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved