

A297139


Numbers whose base7 digits d(m), d(m1),..., d(0) have m=0 or else d(i) = d(i+1) for some i in {0,1,...,m1}.


4



1, 2, 3, 4, 5, 6, 8, 16, 24, 32, 40, 48, 49, 56, 57, 58, 59, 60, 61, 62, 65, 73, 81, 89, 97, 98, 106, 112, 113, 114, 115, 116, 117, 118, 122, 130, 138, 146, 147, 155, 163, 168, 169, 170, 171, 172, 173, 174, 179, 187, 195, 196, 204, 212, 220, 224, 225, 226
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OFFSET

1,2


COMMENTS

These numbers comprise the complement of the set of numbers in the union of A297137 and A297138.
Differs from A044818 first for 344 = 1001_7. 1001_7 has two runs of length 1 and is not in A044818, but it has a sequence of two consecutive zeros and is in this sequence.  R. J. Mathar, Jan 18 2018


LINKS

Table of n, a(n) for n=1..58.


EXAMPLE

Base7 digits of 4998: 2,0,4,0,0, so that 4998 is in the sequence.


MAPLE

read("transforms") :
isA297139 := proc(n)
local dgs, ud;
dgs := convert(n, base, 7) ;
if nops(dgs) < 2 then
return true;
end if;
if 0 in DIFF(dgs) then
true;
else
false;
end if;
end proc:
for n from 1 to 300 do
if isA297139(n) then
printf("%d, ", n) ;
end if;
end do: # R. J. Mathar, Jan 18 2018


MATHEMATICA

a[n_, b_] := Sign[Differences[IntegerDigits[n, b]]]; z = 300;
b = 7; t = Table[a[n, b], {n, 1, 10*z}];
u = Select[Range[z], ! MemberQ[t[[#]], 0] && First[t[[#]]] == 1 &] (* A297137 *)
v = Select[Range[z], ! MemberQ[t[[#]], 0] && First[t[[#]]] == 1 &] (* A297138 *)
Complement[Range[z], Union[u, v]] (* A297139 *)


CROSSREFS

Cf. A297137, A297138.
Sequence in context: A039089 A044956 A044818 * A048304 A043710 A296703
Adjacent sequences: A297136 A297137 A297138 * A297140 A297141 A297142


KEYWORD

nonn,easy,base


AUTHOR

Clark Kimberling, Jan 15 2018


STATUS

approved



