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A047389 Numbers that are congruent to {3, 5} mod 7. 6
3, 5, 10, 12, 17, 19, 24, 26, 31, 33, 38, 40, 45, 47, 52, 54, 59, 61, 66, 68, 73, 75, 80, 82, 87, 89, 94, 96, 101, 103, 108, 110, 115, 117, 122, 124, 129, 131, 136, 138, 143, 145, 150, 152, 157, 159, 164, 166, 171 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = 7*n - a(n-1) - 6, n > 1. - Vincenzo Librandi, Aug 05 2010
From Bruno Berselli, Sep 08 2010: (Start)
G.f.: x*(3 + 2*x + 2*x^2)/((1+x)*(1-x)^2).
a(n) - a(n-1) - a(n-2) + a(n-3) = 0 for n > 3.
a(n) = (14*n - 5 - 3*(-1)^n)/4. (End)
E.g.f.: 2 + ((14*x - 5)*exp(x) - 3*exp(-x))/4. - David Lovler, Sep 13 2022
MATHEMATICA
#+{3, 5}&/@(7*Range[0, 30])//Flatten (* Harvey P. Dale, Oct 10 2019 *)
PROG
(PARI) a(n) = (14*n - 5 - 3*(-1)^n)/4 \\ David Lovler, Sep 13 2022
CROSSREFS
Sequence in context: A285415 A275668 A212537 * A263652 A285679 A093661
KEYWORD
nonn,easy
AUTHOR
STATUS
approved

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Last modified March 18 22:50 EDT 2024. Contains 370951 sequences. (Running on oeis4.)