A071191 Least m>n such that the number of prime factors of m and n differ at most by 1.

2, 3, 4, 5, 6, 7, 9, 9, 10, 11, 13, 14, 14, 15, 17, 18, 19, 20, 21, 21, 22, 23, 25, 27, 26, 27, 28, 30, 31, 33, 33, 36, 34, 35, 37, 40, 38, 39, 41, 42, 43, 44, 46, 45, 46, 47, 49, 54, 50, 51, 52, 54, 55, 56, 57, 60, 58, 59, 61, 63, 62, 63, 65

Offset: 1

Author

Reinhard Zumkeller, May 15 2002

Keywords

• nonn

Comments

abs(A001222(a(n)) - A001222(n)) <= 1.

Examples

			a(11) = 13 as 11 has one prime factor (counted with multiplicity) and 13 has 1 prime factor (counted with multiplicity), 13 the smallest number m > 11 such that the number of prime factors of m and 11 differ by at most 1. - _David A. Corneth_, Feb 23 2024
		

Links

• David A. Corneth, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A071192, A071193.

Programs

PARI

a(n) = {
	my(b = bigomega(n));
	for(i = n + 1, oo,
		if(abs(bigomega(i)-b) <= 1,
			return(i)
		)
	)
} \\ David A. Corneth, Feb 23 2024