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 A103126 #21 Mar 14 2025 09:52:00 %S A103126 2030,10203,12110,20210,20310,21004,21010,24000,24010,31010,41001, %T A103126 50010,70000,100004,100012,100210,100310,100320,101020,101041,102022, %U A103126 103200,104010,104101,104110,105020,106001,110020,110202,110212,110400,111013 %N A103126 5-Smith numbers. %H A103126 Amiram Eldar, <a href="/A103126/b103126.txt">Table of n, a(n) for n = 1..10000</a> %H A103126 Shyam Sunder Gupta, <a href="http://www.shyamsundergupta.com/smith.htm">Smith Numbers</a>. %H A103126 Shyam Sunder Gupta, <a href="https://doi.org/10.1007/978-981-97-2465-9_4">Smith Numbers</a>, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 4, 127-157. %H A103126 Wayne L. McDaniel, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/25-1/mcdaniel.pdf">The Existence of infinitely Many k-Smith numbers</a>, Fibonacci Quarterly, Vol. 25, No. 1 (1987), pp. 76-80. %e A103126 2030 is a 5-Smith number because the sum of the digits of its prime factors, i.e., Sp(2030) = Sp(2*5*7*29) = 2 + 5 + 7 + 2 + 9 = 25, which is equal to 5 times the digit sum of 2030, i.e., 5*S(2030) = 5*(2 + 0 + 3 + 0) = 25. %t A103126 digSum[n_] := Plus @@ IntegerDigits[n]; fiveSmithQ[n_] := CompositeQ[n] && Plus @@ (Last@# * digSum[First@#] & /@ FactorInteger[n]) == 5 *digSum[n]; Select[Range[10^5], fiveSmithQ] (* _Amiram Eldar_, Aug 23 2020 *) %Y A103126 Cf. A006753. %K A103126 base,nonn %O A103126 1,1 %A A103126 _Shyam Sunder Gupta_, Mar 16 2005