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A121743 Values of the Ramanujan tau triples mod 691 such that three consecutive Ramanujan tau numbers are congruent mod 691. 7

%I #22 Nov 03 2020 02:36:59

%S 0,276,91,79,0,0,0,0,76,349,212,355,662,227,342,616,182,641,105,0,21,

%T 33,0,0,316,436,346,109,468,557,261,512,299,532,565,214,72,218,436,0,

%U 166,532,0,591,0,144,0,544,257,0,0,0,422,0,0,488,0,0,0,488,0,233,371,0,380,28,0,641,414,331,0,487,0,666,130,14,0,0,321,620,0,339,533

%N Values of the Ramanujan tau triples mod 691 such that three consecutive Ramanujan tau numbers are congruent mod 691.

%C Corresponding indices of the Ramanujan tau triples mod 691 are listed in A121742. All a(n) belong to the Ramanujan tau twins mod 691 A121734(n). 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.

%H Jud McCranie, <a href="/A121743/b121743.txt">Table of n, a(n) for n = 1..2568</a>

%H Eric Weisstein <a href="http://mathworld.wolfram.com/TauFunction.html">Ramanujan's Tau Function</a>.

%F a(n) = A000594(A121742(n)) mod 691.

%F a(n) = A046694(A121742(n)).

%t 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}]

%t Select[Partition[Table[Mod[DivisorSigma[11,n],691],{n,10000000}],3,1],Length[ Union[#]]==1&][[All,1]] (* _Harvey P. Dale_, Jan 31 2020 *)

%Y Cf. A000594, A046694, A121733, A121734, A121742.

%K nonn

%O 1,2

%A _Alexander Adamchuk_, Aug 19 2006

%E a(7)-a(16) from _Amiram Eldar_, Jan 26 2020

%E More terms by _Jud McCranie_ Nov 02 2020

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Last modified April 18 20:26 EDT 2024. Contains 371781 sequences. (Running on oeis4.)