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A121734 Ramanujan tau numbers such that A000594[n] == A000594[n+1] mod 691, or A046694[n] = A046694[n+1]. 6
483, 209, 21, 632, 650, 541, 546, 281, 666, 440, 397, 576, 18, 251, 356, 207, 532, 361, 121, 642, 288, 167, 348, 505, 561, 0, 108, 166, 97, 492, 58, 255, 632, 151, 679, 185, 141, 587, 0, 549, 459, 428, 549, 157, 559, 121, 605, 102 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Corresponding indices n are listed in A121733[n] = {184,2103,3421,3638,4342,5181,6029,6233,8323,8628,8721,9658,9905,...}.

LINKS

Table of n, a(n) for n=1..48.

Eric Weisstein's World of Mathematics, Ramanujan's Tau Function.

FORMULA

a(n) = mod[ A000594[ A121733[n] ], 691] = A046694[ A121733[n] ].

EXAMPLE

a(1) = 483 because the first pair of equal consecutive numbers in A046694[n] is A046694[184] = A046694[185] = 483.

MATHEMATICA

Do[f=Mod[DivisorSigma[11, n], 691]; g=Mod[DivisorSigma[11, n+1], 691]; If[f==g, Print[{n, f}]], {n, 1, 10000}]

CROSSREFS

Cf. A121733, A046694, A000594.

Sequence in context: A158329 A231395 A263291 * A260976 A281047 A158330

Adjacent sequences:  A121731 A121732 A121733 * A121735 A121736 A121737

KEYWORD

nonn

AUTHOR

Alexander Adamchuk, Aug 18 2006

STATUS

approved

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Last modified January 19 16:08 EST 2019. Contains 319307 sequences. (Running on oeis4.)