OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..10000
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
Sum_{k>=0} 1/a(k) = 4*sqrt(10-22/sqrt(5))*Pi/5. - Jaume Oliver Lafont, May 22 2010
G.f.: (1 + 121*x + 381*x^2 + 121*x^3 + x^4)/(1-x)^5. - Colin Barker, Aug 17 2012
Sum_{n>=0} (-1)^n/a(n) = 32*log(2)/5 - 8*arccoth(3/sqrt(5))/sqrt(5). - Amiram Eldar, Sep 20 2022
MATHEMATICA
(Times@@#)/24&/@Table[5n+i, {n, 0, 35}, {i, 4}] (* Harvey P. Dale, Aug 16 2011 *)
Table[Binomial[5*n+4, 4], {n, 0, 30}] (* G. C. Greubel, Nov 08 2018 *)
PROG
(Magma) [(5*n+1)*(5*n+2)*(5*n+3)*(5*n+4)/24: n in [0..30]]; // Vincenzo Librandi, Aug 17 2011
(PARI) vector(30, n, n--; binomial(5*n+4, 4)) \\ G. C. Greubel, Nov 08 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
M. F. Hasler, Sep 14 2009
STATUS
approved