A167611 Nonprimes that are the sum of two consecutive nonprimes.

1, 10, 14, 22, 26, 34, 38, 46, 49, 51, 55, 58, 62, 65, 69, 74, 77, 82, 86, 91, 94, 99, 106, 111, 115, 118, 122, 125, 129, 134, 142, 146, 153, 155, 158, 161, 166, 169, 171, 175, 178, 183, 185, 187, 189, 194, 202, 206, 209, 214, 218, 221, 226, 231, 235, 237, 243

Offset: 1

Author

Juri-Stepan Gerasimov, Nov 07 2009

Keywords

• nonn

Comments

One and composite numbers that are the sum of two consecutive composite numbers.

Essentially the same as A151740 (except for initial term 1). - Georg Fischer, Oct 01 2018

Examples

			a(1) = 1st nonprime + 2nd nonprime = 0 + 1 =  1, which is nonprime;
a(2) = 3rd nonprime + 4th nonprime = 4 + 6 = 10, which is nonprime.
		

Links

• Karl-Heinz Hofmann, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A018252, A141468, A151740.

Programs

Magma

m:=150; NonPrime:=[i: i in [0..m] | not IsPrime(i)]; [q: n in [1..#NonPrime-1] | not IsPrime(q) where q is NonPrime[n]+NonPrime[n+1]]; // Bruno Berselli, Apr 05 2014

Python

from sympy import isprime, composite
print([1] + [totest for k in range(1,91) if not isprime(totest := composite(k) + composite(k+1))]) # Karl-Heinz Hofmann, Jan 25 2024

Extensions

Entries confirmed by R. J. Mathar, May 30 2010