The OEIS is supported by the many generous donors to the OEIS Foundation.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #18 Mar 25 2024 12:05:49
%S 1,176,231,495,7040
%N Base-12 numbers k such that k = (product of nonzero digits of k) * (sum of digits of k) (written in base 10).
%C There are only finitely many such numbers (Property 1' of Clerc).
%H René-Louis Clerc, <a href="https://hal.science/hal-04235744">Quelques nombres de Niven-Harshad particuliers</a>, 2023.
%H René-Louis Clerc, <a href="https://ut3-toulouseinp.hal.science/hal-04507547">Nombres S+P, maxSP, minSP et |P-S|</a>, hal-04507547 [math.nt], 2024. (In French)
%e 231 = 173_12, (1*7*3)*(1+7+3) = 21*11 = 231.
%t Select[Range[5*10^4], Total[IntegerDigits[#, 12]]*Fold[Times, 1, Select[IntegerDigits[#, 12],#>0&]]==#&] (* _James C. McMahon_, Feb 14 2024 *)
%o (PARI) isok(k, b) = my(d=select(x->(x>0), digits(k, b))); vecprod(d)*vecsum(d) == k;
%o for (k=0, 10^10, if (isok(k, 12), print1(k, ", ")))
%Y Cf. A366832, A367070, A066282, A062331, A023651, A038364, A038369, A062237.
%K base,nonn,fini,more
%O 1,2
%A _René-Louis Clerc_, Feb 13 2024