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A236692 Numbers n such that n+1, 2n+1 and n^2+1 are primes. 1
1, 2, 6, 36, 156, 210, 270, 306, 576, 690, 936, 966, 2136, 2310, 2550, 2706, 2850, 3390, 3966, 4026, 4176, 4260, 4566, 4590, 5226, 5430, 5850, 6120, 6216, 6360, 6420, 6546, 7410, 7536, 8940, 9126, 9240, 9276, 9900, 10530, 10836, 11286, 11586, 11886, 12390, 13680 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[14000], AllTrue[{#+1, 2#+1, #^2+1}, PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 27 2019 *)

PROG

(Python)

import sympy

from sympy import isprime

for n in range(100000):

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

(PARI)

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

CROSSREFS

Cf. A005382, A070689.

Sequence in context: A127564 A130874 A019020 * A323945 A101609 A281024

Adjacent sequences:  A236689 A236690 A236691 * A236693 A236694 A236695

KEYWORD

nonn

AUTHOR

Alex Ratushnyak, Jan 30 2014

STATUS

approved

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Last modified October 22 10:18 EDT 2020. Contains 337950 sequences. (Running on oeis4.)