OFFSET
1,1
COMMENTS
Numbers congruent to 19 or 39 modulo 42. - Jianing Song, Apr 27 2022
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..10000
Index entries for linear recurrences with constant coefficients, signature (1,1,-1)
FORMULA
a(n) = A047241(7*n).
From Jianing Song, Apr 27 2022: (Start)
a(n) = a(n-2) + 42.
a(n) = a(n-1) + a(n-2) - a(n-3).
G.f.: (19*x+20*x^2+3*x^3)/(1-x-x^2+x^3).
E.g.f.: 3 + (21*x-3)*cosh(x) + (21*x-2)*sinh(x). (End)
PROG
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Antti Karttunen, Jul 27 2015
STATUS
approved