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 A272139 Numbers n such that Bernoulli number B_{n} has denominator 1806. 27
 42, 294, 798, 1806, 2058, 2814, 2982, 4074, 4578, 5334, 5586, 6594, 6846, 8106, 8274, 8358, 9366, 9534, 12642, 12894, 13314, 14154, 14658, 15162, 17178, 18186, 19194, 20118, 20454, 21882, 21966, 22722, 22974, 23982, 25914, 26502, 27006, 28266, 28518, 29778 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS 1806 = 2 * 3 * 7 * 43. All terms are multiple of a(1) = 42. For these numbers numerator(B_{n}) mod denominator(B_{n}) = 1. In 2005, B. C. Kellner proved E. W. Weisstein's conjecture that denom(B_n) = n only if n = 1806. LINKS Seiichi Manyama, Table of n, a(n) for n = 1..1000 EXAMPLE Bernoulli B_{42} is 1520097643918070802691/1806, hence 42 is in the sequence. MAPLE with(numtheory): P:=proc(q, h) local n;  for n from 2 by 2 to q do if denom(bernoulli(n))=h then print(n); fi; od; end: P(10^6, 1806); MATHEMATICA Select[Range[0, 1000], Denominator[BernoulliB[#]] == 1806 &] (* Robert Price, Apr 21 2016 *) Select[Range[42, 30000, 42], Denominator[BernoulliB[#]]==1806&] (* Harvey P. Dale, Jun 01 2019 *) PROG (PARI) lista(nn) = for(n=1, nn, if(denominator(bernfrac(n)) == 1806, print1(n, ", "))); \\ Altug Alkan, Apr 22 2016 CROSSREFS Cf. A045979, A051222, A051225, A051226, A051227, A051228, A051229, A051230, A119456, A119480, A249134, A255684, A271634, A271635, A272138,  A272140, A272183, A272184, A272185, A272186. Sequence in context: A190534 A248466 A233407 * A167654 A095266 A232338 Adjacent sequences:  A272136 A272137 A272138 * A272140 A272141 A272142 KEYWORD nonn AUTHOR Paolo P. Lava, Apr 21 2016 EXTENSIONS More terms from Altug Alkan, Apr 22 2016 STATUS approved

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Last modified January 28 21:00 EST 2022. Contains 350663 sequences. (Running on oeis4.)