A106125 Numbers k such that k divides the k-th semiprime.

1, 2, 3, 7, 11, 43, 53, 613367, 613439, 613451, 613523, 613549, 613609, 6384425461, 6384425521, 6384425569, 6384425647

Offset: 1

Author

Shyam Sunder Gupta, May 07 2005

Keywords

• nonn
• hard
• more

Comments

Note that except 1, all other term in the sequence will be primes.

a(18) > 10^12. - Lucas A. Brown, Oct 17 2020

Examples

			a(4)=7 is a term because 7 divides the 7th semiprime (i.e., 21).
		

Links

• Lucas A. Brown, semiprimemods.py

Crossrefs

Cf. A001358, A356764, A357741.

Extensions

a(14)-a(17) from Donovan Johnson, Sep 27 2010