A043107 Numbers k such that 0 and 2 occur juxtaposed in the base-5 representation of k but not of k-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
Offset: 1
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Crossrefs
Cf. A007091.
Programs
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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
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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 *)
Comments