The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A121743 Values of the Ramanujan tau triples mod 691 such that three consecutive Ramanujan tau numbers are congruent mod 691. 7
 0, 276, 91, 79, 0, 0, 0, 0, 76, 349, 212, 355, 662, 227, 342, 616, 182, 641, 105, 0, 21, 33, 0, 0, 316, 436, 346, 109, 468, 557, 261, 512, 299, 532, 565, 214, 72, 218, 436, 0, 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 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. LINKS Jud McCranie, Table of n, a(n) for n = 1..2568 Eric Weisstein Ramanujan's Tau Function. FORMULA a(n) = A000594(A121742(n)) mod 691. a(n) = A046694(A121742(n)). 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}] Select[Partition[Table[Mod[DivisorSigma[11, n], 691], {n, 10000000}], 3, 1], Length[ Union[#]]==1&][[All, 1]] (* Harvey P. Dale, Jan 31 2020 *) CROSSREFS Cf. A000594, A046694, A121733, A121734, A121742. Sequence in context: A133536 A224109 A075666 * A084802 A309998 A003903 Adjacent sequences:  A121740 A121741 A121742 * A121744 A121745 A121746 KEYWORD nonn AUTHOR Alexander Adamchuk, Aug 19 2006 EXTENSIONS a(7)-a(16) from Amiram Eldar, Jan 26 2020 More terms by Jud McCranie Nov 02 2020 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 13 19:36 EDT 2021. Contains 343868 sequences. (Running on oeis4.)