

A118499


Numbers n such that the nth prime number is not a Chen prime.


0



14, 18, 21, 22, 25, 27, 36, 38, 40, 44, 48, 50, 53, 58, 59, 61, 65, 67, 70, 73, 74, 76, 78, 82, 84, 85, 88, 90, 99, 101, 108, 110, 111, 112, 114, 117, 121, 122, 125, 127, 129, 130, 131, 134, 137, 143, 147, 149, 153, 155, 158, 163, 168, 170
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..54.


EXAMPLE

97 is a prime number but not a Chen prime since 99 = 3*3*11.
97 is the 25th prime number, therefore 25 is in the sequence.


MAPLE

ts_inde_nonchen:= proc(n) local i, ans, inde; ans:=[ ]: inde := 0; for i from 1 to n do if ( isprime(i) = 'true') then inde:=inde+1: if (isprime(i+2) = 'false' and numtheory[bigomega](i+2) <> 2) then ans:=[ op(ans), inde ] fi fi od: return ans end: ts_inde_nonchen(2000);


MATHEMATICA

Select[Range[180], Sum[FactorInteger[Prime[ # ]+2][[i, 2]], {i, 1, Length[ FactorInteger[Prime[ # ] + 2]]}] > 2 &]


CROSSREFS

Cf. A102540, A109611.
Sequence in context: A060504 A052026 A317743 * A111205 A097324 A051419
Adjacent sequences: A118496 A118497 A118498 * A118500 A118501 A118502


KEYWORD

nonn


AUTHOR

Jani Melik, May 05 2006


EXTENSIONS

Edited by Stefan Steinerberger, Jul 19 2007


STATUS

approved



