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 A249047 #12 Dec 25 2021 18:35:23 %S A249047 1,5,7,20,31,53,64,86,97,110,121,143,154,176,187,209,211,233,244,266, %T A249047 277,299,310,323,334,356,367,389,400,413,424,446,457,479,490,512,514, %U A249047 536,547,569,580,602,613,626,637,659,670,692,703,716 %N A249047 Self-numbers (A003052) that are not divisible by 3. %D A249047 D. R. Kaprekar, The Mathematics of the New Self Numbers, Privately printed, 311 Devlali Camp, Devlali, India, 1963. %H A249047 Reinhard Zumkeller, <a href="/A249047/b249047.txt">Table of n, a(n) for n = 1..10000</a> %H A249047 D. R. Kaprekar, <a href="/A003052/a003052_2.pdf">The Mathematics of the New Self Numbers</a> [annotated and scanned] %o A249047 (Haskell) %o A249047 a249047 n = a249047_list !! (n-1) %o A249047 a249047_list = filter ((> 0) . flip mod 3) a003052_list %o A249047 -- _Reinhard Zumkeller_, Oct 31 2014 %Y A249047 Cf. A003052, A249045-A249048. %K A249047 nonn,base %O A249047 1,2 %A A249047 _N. J. A. Sloane_, Oct 30 2014