A167915 -id:A167915 - cp's OEIS frontend

A166037 Numbers that are the sum of 2 successive nonprimes A141468.

1, 5, 10, 14, 17, 19, 22, 26, 29, 31, 34, 38, 41, 43, 46, 49, 51, 53, 55, 58, 62, 65, 67, 69, 71, 74, 77, 79, 82, 86, 89, 91, 94, 97, 99, 101, 103, 106, 109, 111, 113, 115, 118, 122, 125, 127, 129, 131, 134, 137, 139, 142, 146, 149, 151, 153, 155, 158, 161, 163, 166

Offset: 1

Juri-Stepan Gerasimov, Oct 05 2009

nonn

a(n) = (n-1)-th nonprimes + (n-1)-th composites for n >= 2. a(n) = A018252(n-1) + A002808(n-1) for n >= 2. - Jaroslav Krizek, Dec 13 2009

			a(1) = 0 + 1 =  1;
a(2) = 1 + 4 =  5;
a(3) = 4 + 6 = 11.

Harvey P. Dale, Table of n, a(n) for n = 1..10000

Cf. A001043, A141468.

Cf. A167915 (primes that are the sums of two consecutive composites).

A002808 := proc(n) option remember; if n = 1 then 4; else for a from procname(n-1)+1 do if not isprime(a) then return a; fi; od: fi; end: A141468 := proc(n) if n <= 2 then n-1 ; else A002808(n-2) ; fi; end: A166037 := proc(n) A141468(n)+A141468(n+1) ; end: seq(A166037(n),n=1..120) ; # R. J. Mathar, Oct 10 2009

With[{nn=100},Join[{1},Total/@Partition[Complement[Range[nn],Prime[ Range[ PrimePi[ nn]]]],2,1]]] (* Harvey P. Dale, Aug 03 2014 *)

A176902 Primes p such that p-1 and p+1 are both non-semiprime.

Original entry on oeis.org

2, 17, 19, 29, 31, 41, 43, 53, 67, 71, 79, 89, 97, 101, 103, 109, 113, 127, 131, 137, 139, 149, 151, 163, 173, 181, 191, 197, 199, 211, 223, 229, 233, 239, 241, 251, 257, 269, 271, 281, 283, 293, 307, 311, 317, 331, 337, 349, 353, 367, 373, 379, 389, 401, 409

Offset: 1

Juri-Stepan Gerasimov, Apr 28 2010

nonn

2 together with A060254.

			a(1)=2 because 2-1=1=non-semiprime and 2+1=3=non-semiprime.

a(n+1)=A060254(n)=A167915(n+1).

Corrected (233, 239 inserted, 279 and 289 replaced by 379 and 389) by R. J. Mathar, Aug 12 2010

cp's OEIS Frontend

A166037 Numbers that are the sum of 2 successive nonprimes A141468.

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