A111298 - OEIS

A111298

Begin with first number 15. Add the digits of the first number to give the second; the first number multiplied by the second gives the third. The third number becomes the first in a new "set" of three.

%I #8 May 30 2024 16:11:52

%S 15,6,90,9,810,9,7290,18,131220,9,1180980,27,31886460,36,1147912560,

%T 36,41324852160,36,1487694677760,72,107114016798720,54,

%U 5784156907130880,72,416459297313423360,72,29985069406566481920,99,2968521871250081710080

%N Begin with first number 15. Add the digits of the first number to give the second; the first number multiplied by the second gives the third. The third number becomes the first in a new "set" of three.

%t a[0]=15;Do[a[n]=Total[IntegerDigits[a[n-1]]];a[n+1]=a[n-1]*a[n],{n,1,28,2}];Table[a[n],{n,0,28}] (* _James C. McMahon_, May 07 2024 *)

%K nonn,base

%O 0,1

%A Chris Dawson (chris(AT)irjsoftware.com), based on an email from Graham Rees, Nov 02 2005

%E More terms from _R. J. Mathar_, Feb 08 2008

%E Name edited by _Michel Marcus_, May 08 2024