A072826 Primes p such that p-1 is a highly composite number.

2, 3, 5, 7, 13, 37, 61, 181, 241, 2521, 7561, 15121, 20161, 45361, 55441, 110881, 332641, 498961, 4324321, 14414401, 43243201, 110270161, 183783601, 367567201, 4655851201, 13967553601, 73329656401, 293318625601, 1606268664001

Offset: 1

Author

Shyam Sunder Gupta, Jul 21 2002

Keywords

• nonn

Examples

			13 is a term because it is a prime such that 13-1=12 is a highly composite number.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..431 (terms below 10^1000; terms 1..300 from T. D. Noe)
• Benny Lim, Prime Numbers Generated From Highly Composite Numbers, Parabola Magazine, volume 54, issue 3, 2018.

Crossrefs

Cf. A002182 (highly composite numbers), A072828 (with p+1 instead), A306587.

Formula

a(n) = A002182(A306587(n)) + 1. - Amiram Eldar, Dec 03 2020