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 A070192 Numbers k such that k divides the numerator of B(2k) (the Bernoulli numbers), but gcd(3k, 8^k+1) > 3. 4

%I #13 Aug 21 2021 19:55:30

%S 301,737,1505,1655,2107,3197,3311,3913,5117,5159,5219,5719,6275,6923,

%T 7385,7513,7525,8107,8275,8729,9331,9581,9835,10535,10849,11137,11585,

%U 12341,12529,12943,13301,14003,14147,14749,15953,15985,17759,18361

%N Numbers k such that k divides the numerator of B(2k) (the Bernoulli numbers), but gcd(3k, 8^k+1) > 3.

%C Equivalently, k is in A069040 but not in A070191.

%t testb[n_] := Select[First/@FactorInteger[n], Mod[2n, #-1]==0&]=={}; test8[n_] := GCD[3n, PowerMod[8, n, 3n]+1]==3; Select[Range[19000], testb[ # ]&&!test8[ # ]&]

%Y Cf. A069040, A070191, A070193.

%K nonn,more

%O 1,1

%A _Benoit Cloitre_ and _Dean Hickerson_, Apr 26 2002

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Last modified April 15 14:58 EDT 2024. Contains 371692 sequences. (Running on oeis4.)