

A152908


Primes p=prime(k) such that p  nonprime(k) is prime and p + nonprime(k) is not prime, where prime(n) is the nth prime and nonprime(n) is the nth nonprime starting with nonprime(1) = 0.


1



3, 17, 37, 53, 71, 79, 113, 127, 151, 167, 277, 317, 383, 397, 419, 421, 509, 577, 599, 641, 643, 653, 683, 761, 797, 829, 877, 937, 1049, 1051, 1087, 1097, 1163, 1249, 1283, 1297, 1367, 1439, 1483, 1607, 1699, 1913, 1933, 1993, 2017, 2081, 2089, 2129, 2131
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..49.


EXAMPLE

3(2)  1(2) = 2 (prime) and 3(2) + 1(2) = 4 (nonprime), so 3 is in the sequence.
17(7)  10(7) = 7 (prime) and 17(7) + 10(7) = 27 (nonprime), so 17 is in the sequence.
37(12)  18(12) = 19 (prime) and 37(12) + 18(12) = 55 (nonprime), so 37 is in the sequence.
53(16)  24(16) = 29(prime) and 53(16) + 24(16) = 77 (nonprime), so 53 is in the sequence.
71(20)  28(20) = 43(prime) and 71(20) + 28(20) = 99 (nonprime), so 71 is in the sequence.


MAPLE

A141468 := proc(n) option remember ; local a; if n = 1 then 0 ; else for a from procname(n1)+1 do if not isprime(a) then RETURN(a) ; fi; od; fi; end: for n from 1 to 700 do p := ithprime(n) ; if isprime( p A141468(n)) and not isprime(p+A141468(n)) then printf("%d, ", p) ; fi; od: # R. J. Mathar, Jan 17 2009


CROSSREFS

Cf. A000040, A141468, A144517.
Sequence in context: A297735 A266062 A031290 * A031386 A146813 A106895
Adjacent sequences: A152905 A152906 A152907 * A152909 A152910 A152911


KEYWORD

nonn


AUTHOR

JuriStepan Gerasimov, Dec 15 2008


EXTENSIONS

227, 619, 1039, etc. removed, and 797, 1087, etc. added, by R. J. Mathar, Jan 17 2009
Better definition from Michel Marcus, Aug 07 2017


STATUS

approved



