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A043107 Numbers k such that 0 and 2 occur juxtaposed in the base-5 representation of k but not of k-1. 1
10, 27, 35, 50, 60, 77, 85, 102, 110, 127, 135, 152, 160, 175, 185, 202, 210, 227, 235, 250, 277, 285, 300, 310, 327, 335, 352, 360, 377, 385, 402, 410, 425, 435, 452, 460, 477, 485, 502, 510, 527, 535, 550, 560, 577, 585, 602 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MAPLE
has02:= proc(n) local L, i, state;
L:= convert(n, base, 5);
state:= 1;
for i from 1 to nops(L) do
if L[i] = 0 then
if state = 2 then return true
else state:= 0
fi
elif L[i] = 2 then
if state = 0 then return true
else state:= 2
fi
else state:= 1;
fi
od;
false
end proc:
H:= select(has02, {$1..1001}):
sort(convert(H minus map(`+`, H, 1), list)); # Robert Israel, Jan 20 2019
MATHEMATICA
With[{s = Partition[Array[IntegerDigits[#, 5] &, 602], 2, 1]}, Map[FromDigits[#, 5] &, Select[s, And[And[SequenceCount[#1, {0, 2}] == 0, SequenceCount[#1, {2, 0}] == 0], Or[SequenceCount[#2, {0, 2}] > 0, SequenceCount[#2, {2, 0}] > 0]] & @@ # &][[All, -1]] ] ] (* Michael De Vlieger, Jan 20 2019 *)
CROSSREFS
Cf. A007091.
Sequence in context: A301606 A281510 A024168 * A039284 A045177 A043887
KEYWORD
nonn,base
AUTHOR
STATUS
approved

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Last modified July 19 11:36 EDT 2024. Contains 374394 sequences. (Running on oeis4.)