A062969 Numbers k such that abs(d(k)-k-1) is prime, where d(k) is the number of divisors of k.

3, 4, 6, 8, 9, 10, 12, 14, 18, 22, 24, 25, 26, 28, 30, 34, 46, 49, 52, 54, 62, 66, 72, 74, 76, 78, 80, 82, 84, 86, 90, 104, 106, 108, 110, 112, 114, 134, 138, 142, 150, 160, 166, 169, 170, 172, 174, 176, 180, 186, 192, 194, 202, 204, 208, 214, 226, 230, 234, 244, 246

Offset: 1

Author

Jason Earls, Jul 23 2001

Keywords

• easy
• nonn

Examples

			d(300)-300-1 = -283, absolute value of which is prime.
		

Crossrefs

Cf. A062968.

Programs

PARI

j=[]; for(n=1,300, if(isprime(numdiv(n)-n-1),j=concat(j,n))); j