A168132 Numbers m = Sum_{k=1..n} sigma(k)/k such that Sum_{k=1..n} sigma(k)/k is an integer for any k.

1, 2, 7, 9, 14, 52, 149, 213, 673, 1778, 3653, 6831, 9868, 570972, 2835107, 3613594, 47211979, 60418265, 99909506, 1701207282, 4587170542, 10955668024, 29031152874, 114018751785, 813149731047

Offset: 1

Author

Jaroslav Krizek, Nov 18 2009, Dec 04 2009

Keywords

• nonn
• more

Comments

Numbers m = A024916(k)/k such that A024916(k)/k is an integer for any k. If a(14) exist must be bigger than 82000.

Corresponding values of k, and Sum_{k=1..n} sigma(k) are given in A056550 and A168133. [Jaroslav Krizek, Nov 21 2009]

Examples

			Number a(3) = 7 is in sequence because A024916(8)/8 = 56/8 = 7 is an integer for k = 8.
		

Extensions

a(14)-a(25) from Donovan Johnson, Jun 16 2011