A309856 Primes of the form 2*p^3+1 where p is also prime.
17, 251, 2663, 48779, 410759, 715823, 2450087, 6615899, 13935743, 15290747, 23394167, 38930219, 160125983, 219804479, 236741543, 1258845587, 1666475243, 2116179719, 2308641299, 3604970627, 3991233959, 4283401139, 6109873703, 8207369603, 8487319319, 9264815927
Offset: 1
Keywords
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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Maple
f:= proc(n) if isprime(n) and isprime(2*n^3+1) then return 2*n^3+1 fi end proc: map(f, [2,seq(i,i=5..10000,6)]);# Robert Israel, Aug 22 2019
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Mathematica
pp = Join[{2}, Select[Range[5, 10000, 6], PrimeQ[#] && PrimeQ[2#^3 + 1]&]]; 2 pp^3 + 1 (* Jean-François Alcover, Jul 31 2020 *) Select[2*Prime[Range[300]]^3+1,PrimeQ] (* Harvey P. Dale, Dec 09 2024 *)
Formula
a(n) = 1+2*A309857(n)^3.
Comments