login
A047319
Numbers that are congruent to {5, 6} mod 7.
2
5, 6, 12, 13, 19, 20, 26, 27, 33, 34, 40, 41, 47, 48, 54, 55, 61, 62, 68, 69, 75, 76, 82, 83, 89, 90, 96, 97, 103, 104, 110, 111, 117, 118, 124, 125, 131, 132, 138, 139, 145, 146, 152, 153, 159, 160, 166, 167, 173
OFFSET
1,1
FORMULA
From R. J. Mathar, Oct 08 2011: (Start)
a(n) = 1/4 + 7*n/2 - 5*(-1)^n/4.
G.f.: x*(5 + x + x^2) / ( (1+x)*(x-1)^2 ). (End)
E.g.f.: 1 + ((14*x + 1)*exp(x) - 5*exp(-x))/4. - David Lovler, Sep 26 2022
PROG
(PARI) a(n) = (14*n + 1 - 5*(-1)^n)/4 \\ David Lovler, Sep 26 2022
CROSSREFS
Sequence in context: A099641 A207189 A285404 * A244368 A185031 A138925
KEYWORD
nonn,easy
STATUS
approved