A115892 Numbers k such that sigma(k)*phi(k) is a palindrome.

1, 2, 3, 69, 219, 221, 224, 254, 1772, 2181, 15463, 50807, 63551, 94236, 161257, 602962, 2105689, 8371756, 2115856505, 2539027806, 5472276593, 6819131191, 15442198064, 16190055003, 46870943027

Offset: 1

Author

Giovanni Resta, Feb 06 2006

Keywords

• nonn
• base

Comments

a(26) > 5*10^10. 205447718981 is also a term. - Donovan Johnson, Sep 30 2011

Examples

			sigma(15463)*phi(15463) = 18056*12972 = 234222432.
		

Crossrefs

Cf. A084122, A115890, A115891.

Extensions

a(19)-a(25) from Donovan Johnson, Sep 30 2011