A152908 Primes p=prime(k) such that p - nonprime(k) is prime and p + nonprime(k) is not prime, where prime(n) is the n-th prime and nonprime(n) is the n-th nonprime starting with nonprime(1) = 0.

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

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(n-1)+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

Juri-Stepan 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