A154896 Sum of proper divisors minus the number of proper divisors of the perfect number A000396(n).

3, 23, 487, 8115, 33550311, 8589869023, 137438691291, 2305843008139952067, 2658455991569831744654692615953842055, 191561942608236107294793378084303638130997321548169039

Offset: 1

Author

Omar E. Pol, Jan 25 2009

Keywords

• nonn

Comments

a(n) is also the difference between the n-th perfect number and its number of proper divisors.

Examples

			a(2) is 23 because the second perfect number is 28 and the sum of proper divisors of 28 is also 28 = 1+2+4+7+14 and the number of proper divisors of 28 is 5, then 28-5 = 23.
		

Crossrefs

Cf. A000396, A001065, A032741, A133033, A152770.

Formula

a(n) = A152770(A000396(n)) = A000396(n)-A133033(n).

Extensions

More terms from Max Alekseyev, Dec 12 2011