A242423 Numbers in whose prime factorization the indices of primes do not sum to a triangular number.

3, 4, 7, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 23, 24, 26, 31, 32, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 45, 49, 50, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 72, 74, 75, 77, 78, 79, 80, 81, 82, 83, 84, 87, 88, 89, 90, 92, 93, 94, 95, 96, 97, 98, 99, 100

Offset: 1

Author

Antti Karttunen, May 16 2014

Keywords

• nonn

Comments

Numbers k such that A010054(A056239(k)) is zero, or equally, such that A002262(A056239(k)) is not zero.

These are numbers such that any iterations of A242424 started from them lead eventually to a cycle greater than one. Please see the comments and references at A242422.

Examples

			3 = p_2 is present, because 2 is not a triangular number.
4 = p_1 * p_1 is present, because 1+1 = 2 is not a triangular number.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..27575

Crossrefs

Complement: A242422.

Cf. A215366, A242424, A000217, A002262, A010054, A056239.