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A321537
Write n in base 10, shorten all the runs of successive identical digits by 1.
3
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, 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, 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
OFFSET
0,23
COMMENTS
More than the usual number of terms are shown in order to reach some interesting terms.
All primes vanish except those in A050758.
EXAMPLE
22 -> 2, so a(22)=2 is the first term > 1.
10 in not reached until a(1100) = 10.
MAPLE
read("transforms"):
A321537 := proc(n)
local dgsin, dgsout, pos ;
dgsin := convert(n, base, 10) ;
dgsout := [] ;
for pos from 2 to nops(dgsin) do
if op(pos, dgsin) = op(pos-1, dgsin) then
dgsout := [op(pos, dgsin), op(dgsout)] ;
end if;
end do:
digcatL(dgsout) ;
end proc: # R. J. Mathar, Nov 14 2018
MATHEMATICA
Array[FromDigits[Join @@ Map[Most, Split@ IntegerDigits@ #]] &, 123] (* Michael De Vlieger, Nov 13 2018 *)
PROG
(Python)
from re import split
def A321537(n):
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
(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
CROSSREFS
A base-10 analog of A318921.
Sequence in context: A028706 A060175 A358480 * A218876 A028621 A226557
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Nov 13 2018
STATUS
approved