

A237759


Numbers n such that either n^2*2^n1 or n^2*2^n+1 is prime, but not both.


0



1, 2, 4, 7, 21, 25, 30, 33, 41, 45, 57, 63, 83, 100, 131, 142, 144, 147, 150, 175, 198, 225, 304, 425, 449, 469, 513, 651, 782, 858, 1345, 1839, 1883, 1913, 2177, 2551, 2907, 3638, 3675, 6071, 6076, 9297, 11037, 11743, 12135, 12876, 14641, 38685, 40857
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OFFSET

1,2


LINKS



EXAMPLE

4 is in the sequence because 4^2*2^4  1 = 16*16  1 = 255 is not a prime number but 4^2*2^4 + 1 = 16*16 + 1 = 257 is a prime number.


PROG

(PARI) isok(n) = isp1 = isprime(2^n*n^21); isp2 = isprime(2^n*n^2+1); (isp1  isp2 && !(isp1 && isp2)); \\ Michel Marcus, Mar 05 2014


CROSSREFS



KEYWORD

nonn,less


AUTHOR



EXTENSIONS



STATUS

approved



