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A144975 Centered heptagonal twin prime numbers. 1

%I #19 Sep 08 2022 08:45:38

%S 43,71,197,463,1933,5741,8233,9283,11173,14561,34651,41203,57793,

%T 68111,84631,104147,139301,168631,207523,244861,307693,333103,357281,

%U 415381,465011,475273,506731,592663,595547,607153,729373,742211,781397,876751

%N Centered heptagonal twin prime numbers.

%H Amiram Eldar, <a href="/A144975/b144975.txt">Table of n, a(n) for n = 1..10000</a>

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Centered_heptagonal_number">Centered heptagonal twin prime numbers</a>

%e 43 is a term since it is centered heptagonal and the greater member of the twin primes pair (41, 43).

%e 71 is a term since it is centered heptagonal and the lesser member of the twin primes pair (71, 73).

%t TwinPrimeQ[n_]:=If[PrimeQ[n],If[PrimeQ[n-2]||PrimeQ[n+2],True,False],False](*TwinPrimeQ*) lst={};Do[p=(7*n^2-7*n+2)/2;If[TwinPrimeQ[p],AppendTo[lst,p]],{n,2*6!}];lst

%o (Magma) [a:k in [1..510]|IsPrime(a) and (IsPrime(a-2) or IsPrime(a+2)) where a is (7*k^2-7*k+2) div 2]; // _Marius A. Burtea_, Jan 30 2020

%Y Cf. A001097, A069099.

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Sep 27 2008

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Last modified March 29 02:13 EDT 2024. Contains 371264 sequences. (Running on oeis4.)