OFFSET
1,7
COMMENTS
See A187180 for details.
LINKS
Ray Chandler, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1).
FORMULA
After the initial block of six 1's, the sequence is quasi-periodic with period 36, increasing by 6 after each block.
From Colin Barker, Jan 31 2020: (Start)
G.f.: x*(1 + x^6 + x^9 - x^10 + x^13 + x^14 - x^15 + x^17 - x^18 + x^20 + x^21 - x^22 + x^25 + x^30 + x^31 - x^32 + x^33 - x^34 + x^35 - 2*x^36 + x^37 - x^38 + x^39 - x^40 + x^41) / ((1 - x)^2*(1 + x)*(1 - x + x^2)*(1 + x^2)*(1 + x + x^2)*(1 - x^2 + x^4)*(1 - x^3 + x^6)*(1 + x^3 + x^6)*(1 - x^6 + x^12)).
a(n) = a(n-1) + a(n-36) - a(n-37) for n>42.
(End)
MATHEMATICA
Join[{1, 1, 1, 1, 1}, LinearRecurrence[{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1}, {1, 2, 2, 2, 3, 2, 2, 2, 3, 4, 3, 3, 4, 3, 3, 4, 5, 4, 4, 4, 5, 5, 5, 5, 5, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7}, 115]] (* Ray Chandler, Aug 26 2015 *)
PROG
(PARI) Vec(x*(1 + x^6 + x^9 - x^10 + x^13 + x^14 - x^15 + x^17 - x^18 + x^20 + x^21 - x^22 + x^25 + x^30 + x^31 - x^32 + x^33 - x^34 + x^35 - 2*x^36 + x^37 - x^38 + x^39 - x^40 + x^41) / ((1 - x)^2*(1 + x)*(1 - x + x^2)*(1 + x^2)*(1 + x + x^2)*(1 - x^2 + x^4)*(1 - x^3 + x^6)*(1 + x^3 + x^6)*(1 - x^6 + x^12)) + O(x^80)) \\ Colin Barker, Jan 31 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Mar 06 2011
STATUS
approved