A255771 Number of distinct prime factors of A220294(n).

1, 1, 1, 2, 2, 1, 2, 2, 4, 2, 2

Offset: 0

Author

Hans Havermann, Mar 06 2015

Keywords

• nonn
• hard
• more

Comments

These are the first differences of A255770.

Examples

			A220294(0) = 3 so a(0) = 1.
A220294(1) = 13 so a(1) = 1.
A220294(2) = 241 so a(2) = 1.
A220294(3) = 97*673 so a(3) = 2.
A220294(4) = 193*22253377 so a(4) = 2.
		

References

• Arthur Engel, Problem-Solving Strategies, Springer, 1998, pages 121-122 (E3, said to be a "recent competition problem from the former USSR").

Links

• factordb, First 20 factorizations of A220294

Crossrefs

Cf. A220161, A220294, A255770, A255772, A275528.

Extensions

Offset changed by Arkadiusz Wesolowski, Aug 01 2016

a(9) was found in 2008 by Geoffrey Reynolds. a(10) was found by Anders Björn and Hans Riesel. - Arkadiusz Wesolowski, Aug 02 2016