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A177835 Primes p for which a smaller prime q exists with A000120(q) >= 2*A000120(p)-1. 2

%I #12 Jul 25 2023 04:04:15

%S 17,37,41,67,73,97,131,137,139,149,163,193,197,257,263,269,277,281,

%T 293,337,353,389,401,449,521,523,547,577,593,641,643,673,769,773,1031,

%U 1033,1039,1049,1051,1061,1063,1069,1091,1093,1097,1109,1123,1129,1153,1163,1171

%N Primes p for which a smaller prime q exists with A000120(q) >= 2*A000120(p)-1.

%C See A177836 for a comparison with A095075.

%H Amiram Eldar, <a href="/A177835/b177835.txt">Table of n, a(n) for n = 1..10000</a>

%p read("transforms") ;A000120 := proc(n) wt(n) ; end proc:

%p isA177835 := proc(p) if isprime(p) then q := 2 ; while q < p do if A000120(q) >= 2*A000120(p)-1 then return true; end if; q := nextprime(q) ; end do: return false; else false; end if; end proc:

%p for i from 1 to 2000 do if isA177835(ithprime(i)) then printf("%d,",ithprime(i)) ; end if; end do: # _R. J. Mathar_, May 31 2010

%t With[{b = DigitCount[Prime[Range[200]], 2, 1]}, Rest@ Prime[Position[2*b - 1 - FoldList[Max, b], _?(# <= 0 &)] // Flatten]] (* _Amiram Eldar_, Jul 25 2023 *)

%Y Cf. A000120, A014499, A095075, A061712, A177768, A177836.

%K nonn,easy,base

%O 1,1

%A _Vladimir Shevelev_, May 14 2010

%E keyword:base and more terms added by _R. J. Mathar_, May 31 2010

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Last modified April 24 11:21 EDT 2024. Contains 371936 sequences. (Running on oeis4.)