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n sets a new record for number of iterations of A034690 (sum of digits of the divisors of n) needed to reach 15 (see A086793).
6

%I #16 Dec 21 2024 22:11:42

%S 2,5,9,10,16,18,34,36,66,162,924,71820,127005777360

%N n sets a new record for number of iterations of A034690 (sum of digits of the divisors of n) needed to reach 15 (see A086793).

%C 323203999999676796 takes 22 iterations to reach 15, but it probably is not the next term.

%C One could prefix a(0)=1 and change the definition to "... reach a fixed point, 1 or 15." - _M. F. Hasler_, Nov 08 2015

%H Eric Angelini et al., <a href="/A086793/a086793.txt">List the dividers [sic], sum the digits</a>, lost messages reconstructed by _N. J. A. Sloane_, Dec 21 2024

%o (PARI) m=0;for(n=1,9e9, A086793(n)>m||next;m=A086793(n);print1(n","))

%Y Cf. A034690, A086793, A094501.

%K more,nonn,base

%O 1,1

%A _Jason Earls_, Jun 03 2004

%E Offset corrected and a(13) from _Donovan Johnson_, Oct 28 2010