This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A366832 #25 Mar 25 2024 12:05:42 %S A366832 1,12,1536,172032,430080,4014080 %N A366832 Numbers k such that k = (product of nonzero digits) * (sum of digits) for the digits of k in base 9. %C A366832 There is a finite number of such numbers (Property 1' of Clerc). %H A366832 René-Louis Clerc, <a href="https://hal.science/hal-04235744">Quelques nombres de Niven-Harshad particuliers</a>, 2023. %H A366832 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 A366832 430080 = 724856_9, (7+2+4+8+5+6)*(7*2*4*8*5*6) = 32*13440 = 430080. %t A366832 Select[Range[5*10^6],Total[IntegerDigits[#,9]]*Fold[Times,1,IntegerDigits[#,9]]==#&] (* _James C. McMahon_, Jan 30 2024 *) %o A366832 (PARI) isok(k, b) = my(d=select(x->(x>0), digits(k,b))); vecprod(d)*vecsum(d) == k; %o A366832 for (k=1, 10^7, if (isok(k, 9), print1(k, ", "))) %Y A366832 Cf. A066282, A062331, A023651, A038364, A038369, A062237. %K A366832 base,nonn,fini,more %O A366832 1,2 %A A366832 _René-Louis Clerc_, Jan 10 2024