OFFSET
1,1
COMMENTS
Second bisection of A175898.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) + 140 for n > 4; a(1)=6, a(2)=76, a(3)=386, a(4)=1251.
G.f.: x*(6 + 46*x + 66*x^2 + 21*x^3 + x^4)/(1-x)^5.
a(-n+1) = A181342(n). - Bruno Berselli, Aug 23 2011
MATHEMATICA
LinearRecurrence[{5, -10, 10, -5, 1}, {6, 76, 386, 1251, 3126}, 30] (* Harvey P. Dale, Dec 06 2016 *)
PROG
(Magma) [ (35*n^4-35*n^3+55*n^2-25*n+6)/6: n in [1..30] ];
(PARI) a(n)=(35*n^4-35*n^3+55*n^2-25*n+6)/6 \\ Charles R Greathouse IV, Jul 06 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Klaus Brockhaus, Oct 14 2010
STATUS
approved