OFFSET
1,1
LINKS
Rémy Sigrist, C program for A340495
FORMULA
The sequence a(n)-4*a(n-1) appears to be -5, -4, 1, 6, 11, 16, 21, 26, 31, 36, 41, 46, ... which is essentially 5*k+1 (k >= -1). The sequence itself appears to have g.f. =
x*(2*x-1)*(2*x^2+5*x-2)/((1-x)^2*(1-4*x)).
PROG
(C) See Links section.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Rémy Sigrist and N. J. A. Sloane, Jan 10 2021
STATUS
approved