A154862 - OEIS

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A154862

Nonprimes of the form prime(prime(n)) - 2*n.

1, 1, 9, 21, 45, 51, 65, 105, 133, 153, 209, 243, 247, 325, 357, 385, 413, 459, 495, 531, 675, 707, 729, 789, 805, 845, 891, 913, 951, 981, 1003, 1067, 1083, 1111, 1125, 1203, 1313, 1335, 1347, 1369, 1395, 1417, 1557, 1625, 1703, 1725, 1935, 1967, 2133, 2211

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..50.

MAPLE

for n from 1 to 100 do p := ithprime(ithprime(n))-2*n ; if not isprime(p) then printf("%d, ", p) ; fi; od: # R. J. Mathar, Jan 18 2009

MATHEMATICA

Select[Table[Prime[Prime[n]] - 2 n, {n, 80}], ! PrimeQ[#] &] (* Vincenzo Librandi, Jan 08 2019 *)

PROG

(Magma) [a: n in [1..100] | not IsPrime(a) where a is NthPrime(NthPrime(n)) -2*n]; // Vincenzo Librandi, Jan 08 2019

CROSSREFS