1,1

Note that all zeros of A046694(n) have the indices equal to the terms of all arithmetic progressions of the type k*p, where primes p belong to a(n). Thus A046694( k*a(n) ) = 0 for all integer k>0.

Eric Weisstein Link to a section of The World of Mathematics. Ramanujan's Tau Function.

a(1) = 1381 = 2*691 - 1 is a first prime of the form 2m*691 - 1.

Select[ 2*691*Range[ 1000 ] - 1, PrimeQ[ # ] & ]

Cf. A046694 = Ramanujan tau numbers mod 691 = sum of 11-th power of divisors mod 691. Cf. A121733 = Numbers n such that two consecutive Ramanujan tau numbers are congruent mod 691. Cf. A121734 = Ramanujan tau numbers such that A000594[n] == A000594[n+1] mod 691. Cf. A121742 = Numbers n such that three consecutive Ramanujan tau numbers are congruent mod 691. Cf. A121743 = Values of the Ramanujan tau triplets mod 691 such that three consecutive Ramanujan tau numbers are congruent mod 691. Cf. A134670 = Least number k such that A046694 has a string of n consecutive zeros atarting with A046694(k).

Adjacent sequences: A134668 A134669 A134670 this_sequence A134672 A134673 A134674

Sequence in context: A139667 A031796 A020406 this_sequence A134670 A092128 A029819

nonn

Alexander Adamchuk (alex(AT)kolmogorov.com), Nov 05 2007