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A103479
Positive integers k for which 1 + 6*2^(k+2) divides the Fermat number 1 + 2^2^k.
2
OFFSET
1,1
COMMENTS
On Keller's linked page, to find the terms, you run through the tables and find all rows with k = 3 and with n exactly 3 greater than m, then that m belongs to this sequence. - Jeppe Stig Nielsen, Dec 04 2018
EXAMPLE
a(1)=38 because 38 is the smallest positive integer k for which 1 + 6*2^(k+2) divides the Fermat number 1 + 2^2^k.
MATHEMATICA
aQ[n_] := PowerMod[2, 2^n, 1 + 6*2^(n+2)] == 6*2^(n+2); Select[Range[3000000], aQ] (* Amiram Eldar, Dec 04 2018 *)
PROG
(PARI) isOK(n) = Mod(2, 1+3*2^(n+3))^(2^n) + 1 == 0 \\ Jeppe Stig Nielsen, Dec 03 2018
CROSSREFS
Sequence in context: A134182 A110017 A181016 * A036174 A162458 A097439
KEYWORD
nonn,bref,hard,more
AUTHOR
Serhat Sevki Dincer (mesti_mudam(AT)yahoo.com), Feb 07 2005
EXTENSIONS
Sequence name trimmed by Jeppe Stig Nielsen, Dec 03 2018
STATUS
approved