OFFSET
1,1
COMMENTS
Corresponding Ramanujan tau numbers mod 691 are listed in A121743(n) = A046694(a(n)). A121743(n) begins {0,276,91,79,0,0,...}. a(n) are the indices of the first number in the Ramanujan tau triples mod 691. All a(n) belong to A121733(n) - indices of the first number in the Ramanujan tau twins mod 691. There are also quadruplets in the Ramanujan tau mod 691 such that A046694(n) = A046694(n+1) = A046694(n+2) = A046694(n+3). The first such Ramanujan tau quadruplet mod 691 starts with A046694(1409635) = 0.
LINKS
Jud McCranie, Table of n, a(n) for n = 1..2568
Eric Weisstein Ramanujan's Tau Function.
MATHEMATICA
Do[f=Mod[DivisorSigma[11, n], 691]; g=Mod[DivisorSigma[11, n+1], 691]; h=Mod[DivisorSigma[11, n+2], 691]; If[f==g&&g==h, Print[{n, f}]], {n, 1, 1500000}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, Aug 19 2006
EXTENSIONS
a(7)-a(16) from Amiram Eldar, Jan 26 2020
More terms from Jud McCranie, Nov 02 2020
STATUS
approved