OFFSET
0,3
COMMENTS
It appears that if p is a prime of the form 8*r +/- 1, a(p-1) == 0 (mod p); and that if p is a prime of the form 8*r +/- 3, a(p+1) == 0 (mod p).
LINKS
Bruno Berselli, Table of n, a(n) for n = 0..500
Index entries for linear recurrences with constant coefficients, signature (7,-7,1).
FORMULA
G.f.: x*(1+5*x)/((1-x)*(1-6*x+x^2)). [Bruno Berselli, Jun 26 2012]
a(n) = ((1-2*sqrt(2))*(1-sqrt(2))^(2n-1)+(1+2*sqrt(2))*(1+sqrt(2))^(2n-1)-6)/4. [Bruno Berselli, Jun 26 2012]
MATHEMATICA
m = 36; n = 5; c = 0;
list3 = Reap[While[c < 22, t = 6 n - m + 6; Sow[t]; m = n; n = t; c++]][[2, 1]]
PROG
(Magma) [n le 2 select n-1 else 6*Self(n-1)-Self(n-2)+6: n in [1..23]]; // Bruno Berselli, Jun 26 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Kenneth J Ramsey, May 09 2012
EXTENSIONS
Definition rewritten from Bruno Berselli, Jun 26 2012
STATUS
approved