OFFSET
1,1
COMMENTS
This sequence has its first 45 terms in common with A068191.
Subsequence of A068191.
Complement of A063938. - Omar E. Pol, Aug 28 2011
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
B. Ramakrishnan and Brundaban Sahu, Rankin-Cohen brackets and Van der Pol-type identities for the Ramanujan's tau function, arXiv:0711.3512 [math.NT], 2007, pp. 14. See Corollary 2.11
EXAMPLE
For n=1, a(1)=11 since 11 does not divide tau(11) = 534612.
MAPLE
with(numtheory): tn := proc(n) modp(-840*sum(k^4*sigma(k)*sigma(n-k), k=1..n-1), n); end; ser := proc(a, b) local n, lis; lis := []; for n from a to b do if tn(n) <> 0 then lis := [op(lis), n]; fi; od; lis; end;
MATHEMATICA
Select[Range[120], !Divisible[RamanujanTau[#], #]&] (* Jean-François Alcover, Nov 29 2017 *)
PROG
(PARI) isok(k) = ramanujantau(k) % k; \\ Michel Marcus, Aug 14 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Luis H. Gallardo, Jun 08 2011
STATUS
approved