A071192 Least m>n such that the number of prime factors of m and n differ by 1.

2, 4, 4, 5, 6, 7, 9, 9, 11, 11, 14, 14, 14, 17, 17, 18, 21, 21, 21, 21, 23, 23, 25, 27, 27, 27, 33, 33, 33, 33, 33, 36, 37, 37, 37, 42, 38, 41, 41, 42, 46, 46, 46, 46, 46, 47, 49, 54, 50, 51, 52, 54, 55, 63, 59, 63, 59, 59, 62, 63, 62, 63, 65

Offset: 1

Author

Reinhard Zumkeller, May 15 2002

Keywords

• nonn

Examples

			a(11) = 14 as 11 has one prime factor (counted with multiplicity) and 14 has 2 prime factors (counted with multiplicity) 14 the smallest number m > 11 such that the number of prime factors of m and 11 differ by 1. - _David A. Corneth_, Feb 23 2024
		

Links

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

Crossrefs

Cf. A001222, A071191, 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

PARI

a(n) = my(b=bigomega(n), k=n+1); while(abs(bigomega(k) - b) != 1, k++); k; \\ Michel Marcus, Mar 21 2025

Formula

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