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A321537 Write n in base 10, shorten all the runs of successive identical digits by 1.

%I A321537 #24 Nov 29 2018 10:38:38
%S A321537 0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,3,
%T A321537 0,0,0,0,0,0,0,0,0,0,4,0,0,0,0,0,0,0,0,0,0,5,0,0,0,0,0,0,0,0,0,0,6,0,
%U A321537 0,0,0,0,0,0,0,0,0,7,0,0,0,0,0,0,0,0,0,0,8,0,0,0,0,0,0,0,0,0,0,9,0,0,0,0,0,0,0,0,0,0,1,11,1,1,1,1,1,1,1,1,0,0,2,0
%N A321537 Write n in base 10, shorten all the runs of successive identical digits by 1.
%C A321537 More than the usual number of terms are shown in order to reach some interesting terms.
%C A321537 All primes vanish except those in A050758.
%H A321537 Chai Wah Wu, <a href="/A321537/b321537.txt">Table of n, a(n) for n = 0..10000</a>
%e A321537 22 -> 2, so a(22)=2 is the first term > 1.
%e A321537 10 in not reached until a(1100) = 10.
%p A321537 read("transforms"):
%p A321537 A321537 := proc(n)
%p A321537     local dgsin,dgsout,pos ;
%p A321537     dgsin := convert(n,base,10) ;
%p A321537     dgsout := [] ;
%p A321537     for pos from 2 to nops(dgsin) do
%p A321537         if op(pos,dgsin) = op(pos-1,dgsin) then
%p A321537             dgsout := [op(pos,dgsin),op(dgsout)] ;
%p A321537         end if;
%p A321537     end do:
%p A321537     digcatL(dgsout) ;
%p A321537 end proc: # _R. J. Mathar_, Nov 14 2018
%t A321537 Array[FromDigits[Join @@ Map[Most, Split@ IntegerDigits@ #]] &, 123] (* _Michael De Vlieger_, Nov 13 2018 *)
%o A321537 (Python)
%o A321537 from re import split
%o A321537 def A321537(n):
%o A321537     return int('0'+''.join(d[:-1] 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 A321537 (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))); fromdigits(Vec(L))} \\ _Andrew Howroyd_, Nov 13 2018
%Y A321537 A base-10 analog of A318921.
%Y A321537 Cf. A321536, A050758.
%K A321537 nonn,base
%O A321537 0,23
%A A321537 _N. J. A. Sloane_, Nov 13 2018