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%I #15 Apr 25 2023 13:55:22
%S 71,262151,1073741831,302231454903657293676551,
%T 85070591730234615865843651857942052871,
%U 23945242826029513411849172299223580994042798784118791,25711008708143844408671393477458601640355247900524685364822023
%N Primes of the form 8^k + 7. Also, primes of the form 64^m + 7.
%C k=2m, since for odd k, 8^k + 7 is divisible by 3.
%C Prime numbers p in A144242 such that p-1 is the fourth a-gonal and seventh b-gonal number for some a and b. Namely, a = (8^k+14)/6 and b = (8^k + 41)/21.
%C This sequence appears to be a subset of A144313.
%C The next term has 178 digits. - _Harvey P. Dale_, Sep 03 2015
%e 71 - 1 = 70 is the fourth triskaidecagonal number and seventh pentagonal number.
%t Select[64^Range[40]+7,PrimeQ] (* _Harvey P. Dale_, Sep 03 2015 *)
%o (Magma) [a: n in [0..80] | IsPrime(a) where a is 8^n+7]; // _Vincenzo Librandi_, Aug 02 2017
%Y Cf. A000040, A000668, A144231, A144232, A144233, A144234, A144236, A144242, A144245, A144246, A144247, A144313.
%K nonn
%O 1,1
%A _Reikku Kulon_, Sep 18 2008
%E Edited by _Max Alekseyev_, Feb 17 2011