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 A368939 #18 Feb 06 2024 11:55:15 %S A368939 0,1,182380,444992 %N A368939 Numbers k such that the sum of the digits times the sum of the fourth powers of the digits equals k. %C A368939 There are exactly 4 such numbers (Property 16 of Clerc). %H A368939 René-Louis Clerc, <a href="https://hal.science/hal-04235744">Quelques nombres de Niven-Harshad particuliers</a>, 2023. %e A368939 182380 = (1+8+2+3+8)*(1^4 + 8^4 + 2^4 + 3^4 + 8^4) = 22*8290. %t A368939 Select[Range[0,10^7],#==Total[IntegerDigits[#]]*Total[IntegerDigits[#]^4]&] (* _James C. McMahon_, Jan 11 2024 *) %o A368939 (PARI) niven14(k) = my(d=digits(k)); vecsum(d)*sum(i=1, #d, d[i]^4) == k; %o A368939 for(k=1,10^7,if(niven14(k)==1,print1(k,", "))) %Y A368939 Cf. A115518, A257766, A061209, A061210, A254000, A130680, A366507, A366512. %K A368939 nonn,base,fini,full,bref %O A368939 1,3 %A A368939 _René-Louis Clerc_, Jan 10 2024