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A044821 Positive integers having distinct base-10 run lengths. 18
1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 100, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 122, 133, 144, 155, 166, 177, 188, 199, 200, 211, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 233, 244, 255 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
EXAMPLE
117 is in the sequence because it has a run length of 2 and a run length of 1. 101 is not in the sequence because it has three run lengths of 1. - R. J. Mathar, Jan 18 2018
MAPLE
rlset := proc(L::list)
local lset, rl, i ;
lset := [] ;
rl := 1 ;
for i from 2 to nops(L) do
if op(i, L) = op(i-1, L) then
rl := rl+1 ;
else
lset := [op(lset), rl] ;
rl := 1;
end if;
end do:
lset := [op(lset), rl] ;
end proc:
isA044821 := proc(n)
local dgs, rl;
dgs := convert(n, base, 10) ;
rl := rlset(dgs) ;
if nops(rl) = nops( convert(rl, set)) then
true;
else
false;
end if;
end proc:
for n from 1 to 400 do
if isA044821(n) then
printf("%d, ", n) ;
end if;
end do: # R. J. Mathar, Jan 18 2018
PROG
(Python)
from itertools import groupby
def ok(n):
runlengths = [len(list(g)) for k, g in groupby(str(n))]
return len(runlengths) == len(set(runlengths))
print([i for i in range(1, 256) if ok(i)]) # Michael S. Branicky, Jan 04 2021
(PARI) is(n) = { my(runs = List(), lr = 0, d = digits(n)); for(i = 1, #d - 1, if(d[i] != d[i + 1], listput(runs, i - lr); lr = i; ) ); listput(runs, #d - lr); #Set(runs) == #runs } \\ David A. Corneth, Jan 04 2021
CROSSREFS
Sequence in context: A353181 A306273 A141033 * A297148 A048307 A043713
KEYWORD
nonn,base
AUTHOR
STATUS
approved

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Last modified April 14 02:55 EDT 2024. Contains 371652 sequences. (Running on oeis4.)