OFFSET
0,11
EXAMPLE
a(100) = 12, because the 1st run (1) has length 1 and the 2nd run (00) has length 2.
a(13211) = 1112, because the 1st run (1) has length 1, the 2nd run (3) has length 1, the 3rd run (2) has length 1 and the 4th run (11) has length 2.
MATHEMATICA
a[n_] := FromDigits[IntegerDigits[Length /@ Split[IntegerDigits[n]]] // Flatten]; Array[a, 100, 0] (* Amiram Eldar, Feb 16 2022 *)
PROG
(PARI) a(n) = {my(result = "", count = 0, dig = digits(n), last = dig[1]); for(i = 1, length(dig), current = dig[i]; if (current == last, count++, result = concat(result, Str(count)); count = 1); last = current); result = concat(result, Str(count)); return(eval(result))};
(Python)
from itertools import groupby
def A351653(n): return int(''.join(str(len(list(g))) for k, g in groupby(str(n)))) # Chai Wah Wu, Mar 11 2022
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Eder Vanzei, Feb 16 2022
STATUS
approved