A129939 "Self-Lucas"; a(n) is the sum of the last 5 terms. Sequence starts with 12,21,3,1,19 which are l,u,c,a,s if you consider a=1, b=2, c=3, ..., z=26.

12, 21, 3, 1, 19, 56, 100, 179, 355, 709, 1399, 2742, 5384, 10589, 20823, 40937, 80475, 158208, 311032, 611475, 1202127, 2363317, 4646159, 9134110, 17957188, 35302901, 69403675, 136444033, 268241907, 527349704, 1036742220, 2038181539, 4006959403, 7877474773

Offset

1,1

Links

Colin Barker, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (1,1,1,1,1).

Formula

G.f.: x*(-12+18*x^4+35*x^3+30*x^2-9*x)/(-1+x^5+x^4+x^3+x^2+x). - Maksym Voznyy (voznyy(AT)mail.ru), Aug 12 2009

Maple

A129939 := proc(n) option remember ; if n <= 5 then op(n, [12, 21, 3, 1, 19]) ; else add(A129939(n-i), i=1..5) fi ; end: seq(A129939(n), n=1..50) ; # R. J. Mathar, Sep 02 2007

Prog

(PARI) Vec(x*(12+9*x-30*x^2-35*x^3-18*x^4)/(1-x-x^2-x^3-x^4-x^5) + O(x^50)) \\ Colin Barker, Mar 11 2016

Crossrefs

Cf. A129938.

Sequence in context: A377248 A078600 A076638 * A082799 A089320 A227073

Adjacent sequences: A129936 A129937 A129938 * A129940 A129941 A129942

Keyword

base,easy,nonn,word

Author

Eric Angelini, Jun 09 2007

Extensions

More terms from R. J. Mathar, Sep 02 2007

Status

approved