OFFSET
1,1
COMMENTS
a(4) > 10^7.
There is no odd prime p (< 10^7) such that tau(p) is congruent to (p+1)/2 (mod p).
LINKS
Eric Weisstein's World of Mathematics, Tau Function.
Wikipedia, Ramanujan tau function
EXAMPLE
tau(191) = 2762403350592 and 2762403350592 == 95 mod 191, so a(1) = 191.
tau(5399) = -616400667743946780600 and -616400667743946780600 == 2699 mod 5399, so a(2) = 5399.
tau(1259393) = -600367974333827988240021654527358 and -600367974333827988240021654527358 == 629696 mod 1259393, so a(3) = 1259393.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Seiichi Manyama, Dec 16 2017
STATUS
approved