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A236692 Numbers n such that n+1, 2n+1 and n^2+1 are primes. 0


%S 1,2,6,36,156,210,270,306,576,690,936,966,2136,2310,2550,2706,2850,

%T 3390,3966,4026,4176,4260,4566,4590,5226,5430,5850,6120,6216,6360,

%U 6420,6546,7410,7536,8940,9126,9240,9276,9900,10530,10836,11286,11586,11886,12390,13680

%N Numbers n such that n+1, 2n+1 and n^2+1 are primes.

%C Intersection of A070689 and b(n)=A005382(n)-1.

%o (Python)

%o import sympy

%o from sympy import isprime

%o for n in xrange(100000):

%o if isprime(n+1) and isprime(n*2+1) and isprime(n*n+1): print str(n)+',',

%o (PARI)

%o s=[]; for(n=1, 15000, if(isprime(n+1)&&isprime(2*n+1)&&isprime(n^2+1), s=concat(s, n))); s \\ _Colin Barker_, Jan 30 2014

%Y Cf. A005382, A070689.

%K nonn

%O 1,2

%A _Alex Ratushnyak_, Jan 30 2014

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Last modified November 13 08:18 EST 2019. Contains 329093 sequences. (Running on oeis4.)