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 A321536 #23 Nov 13 2018 17:47:48 %S A321536 0,11,22,33,44,55,66,77,88,99,1100,111,1122,1133,1144,1155,1166,1177, %T A321536 1188,1199,2200,2211,222,2233,2244,2255,2266,2277,2288,2299,3300,3311, %U A321536 3322,333,3344,3355,3366,3377,3388,3399,4400,4411,4422,4433,444,4455,4466 %N A321536 Write n in base 10, lengthen all the runs of successive identical digits by 1. %C A321536 A321537(a(n)) = n. Compare A321538. %H A321536 Giovanni Resta, <a href="/A321536/b321536.txt">Table of n, a(n) for n = 0..10000</a> %e A321536 10 -> 1100, so a(10)=1100; 11->111, so a(11)=111. %t A321536 a[n_] := FromDigits@ Flatten[ Append[ #, Last@#] & /@ Split@ IntegerDigits[ n]]; a /@ Range[0, 46] (* _Giovanni Resta_, Nov 13 2018 *) %o A321536 (Python) %o A321536 from re import split %o A321536 def A321536(n): %o A321536 return int(''.join(d+d[0] for d in split('(0+)|(1+)|(2+)|(3+)|(4+)|(5+)|(6+)|(7+)|(8+)|(9+)',str(n)) if d != '' and d != None)) # _Chai Wah Wu_, Nov 13 2018 %o A321536 (PARI) a(n)={my(v=digits(n)); my(L=List()); for(i=1, #v, my(t=v[i]); if(i==1 || t<>v[i-1], listput(L,t)); listput(L,t)); fromdigits(Vec(L))} \\ _Andrew Howroyd_, Nov 13 2018 %Y A321536 A base-10 analog of A175046. %Y A321536 Cf. A321537, A321538. %K A321536 nonn,base,easy %O A321536 0,2 %A A321536 _N. J. A. Sloane_, Nov 13 2018 %E A321536 More terms from _Giovanni Resta_, Nov 13 2018