OFFSET
1,7
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Bertrand Teguia Tabuguia and Wolfram Koepf, FPS In Action: An Easy Way To Find Explicit Formulas For Interlaced Hypergeometric Sequences, arXiv:2207.01031 [cs.SC], 2022.
Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, -1).
FORMULA
G.f.: -x^5*(x^8-6*x^2-1) / (x^12-2*x^6+1). a(n) = 2*a(n-6)-a(n-12). - Colin Barker, Jun 20 2013
a(6n+1) = A016861(n), n>0. a(6n+2) = a(6n+3) = a(6n+4) = 0. a(6n+5)=n+1. - R. J. Mathar, Jun 28 2013
a(n) = Sum_{k=1..n} k*(floor((6k-1)/n)-floor((6k-2)/n)), n>1. - Anthony Browne, Jun 19 2016
MAPLE
A226784 := proc(n)
local x, a, m ;
a := 6 ;
m := 6 ;
if igcd(n, m) > 1 or n =1 then
0;
else
msolve(x*a=1, n) ;
op(%) ;
op(2, %) ;
end if;
end proc: # R. J. Mathar, Jun 28 2013
MATHEMATICA
Inv[a_, mod_] := Which[mod == 1, 0, GCD[a, mod] > 1, 0, True, Last@Reduce[a*x == 1, x, Modulus -> mod]]; Table[Inv[6, n], {n, 1, 122}]
(* Second program: *)
Table[If[GCD[n, 6] != 1, 0, ModularInverse[6, n], 0], {n, 1, 100}] (* Jean-François Alcover, Mar 14 2023 *)
PROG
(PARI) a(n)=if(gcd(n, 6)>1, 0, lift(Mod(1, n)/6)) \\ Charles R Greathouse IV, Jun 18 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
José María Grau Ribas, Jun 18 2013
EXTENSIONS
Name corrected by David A. Corneth, Jun 20 2016
STATUS
approved