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%I #23 Nov 13 2018 17:47:48
%S 0,11,22,33,44,55,66,77,88,99,1100,111,1122,1133,1144,1155,1166,1177,
%T 1188,1199,2200,2211,222,2233,2244,2255,2266,2277,2288,2299,3300,3311,
%U 3322,333,3344,3355,3366,3377,3388,3399,4400,4411,4422,4433,444,4455,4466
%N Write n in base 10, lengthen all the runs of successive identical digits by 1.
%C A321537(a(n)) = n. Compare A321538.
%H Giovanni Resta, <a href="/A321536/b321536.txt">Table of n, a(n) for n = 0..10000</a>
%e 10 -> 1100, so a(10)=1100; 11->111, so a(11)=111.
%t a[n_] := FromDigits@ Flatten[ Append[ #, Last@#] & /@ Split@ IntegerDigits[ n]]; a /@ Range[0, 46] (* _Giovanni Resta_, Nov 13 2018 *)
%o (Python)
%o from re import split
%o def A321536(n):
%o 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 (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 A base-10 analog of A175046.
%Y Cf. A321537, A321538.
%K nonn,base,easy
%O 0,2
%A _N. J. A. Sloane_, Nov 13 2018
%E More terms from _Giovanni Resta_, Nov 13 2018
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