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

1,2

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

Links

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

Example

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

Prog

(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

Crossrefs

Cf. A018252, A141468, A151740.

Sequence in context: A138511 A319802 A244894 * A151740 A136802 A362866

Adjacent sequences: A167608 A167609 A167610 * A167612 A167613 A167614

Keyword

nonn

Author

Juri-Stepan Gerasimov, Nov 07 2009

Extensions

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

Status

approved