A019287 Let sigma_m (n) be result of applying sum-of-divisors function m times to n; call n (m,k)-perfect if sigma_m (n) = k*n; sequence gives the (2,10)-perfect numbers.

480, 504, 13824, 32256, 32736, 1980342, 1396617984, 3258775296, 14763499520, 38385098752

Offset

1,1

Comments

See also the Cohen-te Riele links under A019276.

No other terms < 5*10^11. - Jud McCranie, Feb 08 2012

a(11) > 4*10^12, if it exists. - Giovanni Resta, Feb 26 2020

Links

Table of n, a(n) for n=1..10.

G. L. Cohen and H. J. J. te Riele, Iterating the sum-of-divisors function, Experimental Mathematics, 5 (1996), pp. 93-100.

Crossrefs

Cf. A019278, A019279, A019281, A019282, A019283, A019284, A019285, A019286, A019288, A019289, A019290, A019291.

Sequence in context: A108256 A262222 A115157 * A258551 A257415 A179667

Adjacent sequences: A019284 A019285 A019286 * A019288 A019289 A019290

Keyword

nonn,more

Author

N. J. A. Sloane

Extensions

More terms from Jud McCranie, Nov 13 2001; a(9) Jan 29 2012, a(10) Feb 08 2012

Status

approved