cp's OEIS Frontend

A176255 Numbers of the form 4k-1 with least prime divisor of the form 4m+1.

%I A176255 #19 Sep 08 2022 08:45:52
%S A176255 35,55,95,115,155,175,215,235,247,275,295,299,323,335,355,391,395,403,
%T A176255 415,455,475,515,527,535,559,575,595,611,635,655,695,715,731,755,767,
%U A176255 775,799,815,835,871,875,895,899,923,935,955,995,1003,1015,1027,1055
%N A176255 Numbers of the form 4k-1 with least prime divisor of the form 4m+1.
%C A176255 By definition, all terms are composite numbers.
%H A176255 Amiram Eldar, <a href="/A176255/b176255.txt">Table of n, a(n) for n = 1..10000</a>
%p A176255 A020639 := proc(n) if n = 1 then 1; else min(op(numtheory[factorset](n))) ; end if; end proc:
%p A176255 isA176255 := proc(n) (n mod 4 = 3) and ( A020639(n) mod 4 = 1) ; end proc:
%p A176255 for n from 3 to 1200 by 4 do if isA176255(n) then printf("%d,",n); end if; end do:
%p A176255 # _R. J. Mathar_, Oct 30 2010
%t A176255 Select[4 Range@ 265 - 1, Mod[#, 4] == 1 &[FactorInteger[#][[1, 1]]] &] (* _Michael De Vlieger_, Feb 07 2016 *)
%o A176255 (PARI) isok(n) = ((n % 4) == 3) && ((vecmin(factor(n)[,1]) % 4) == 1); \\ _Michel Marcus_, Feb 07 2016
%o A176255 (Magma) [n: n in [1..1500] |  (n mod 4 eq 3) and (Min(PrimeFactors(n)) mod 4) eq 1]; // _Vincenzo Librandi_, Feb 07 2016
%Y A176255 Cf. A002148, A002145, A016813, A004767.
%K A176255 nonn
%O A176255 1,1
%A A176255 _Vladimir Shevelev_, Apr 13 2010
%E A176255 Terms > 559 from _R. J. Mathar_, Oct 30 2010