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A281004 Numbers with exactly 3 ones in both binary and ternary representations. 2
13, 37, 41, 49, 67, 97, 131, 133, 145, 193, 259, 265, 273, 289, 385, 517, 529, 577, 1027, 1029, 1033, 1041, 1153, 1281, 2053, 2057, 4101, 4105, 4113, 4129, 4161, 6145, 8195, 8197, 8209, 8225, 8257, 8321, 8449, 8705, 10241, 16449, 17409, 18433, 20481, 24577, 32771, 32777, 32785, 32801, 32833, 32897 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Intersection of A014311 and A023694.

All terms are odd, since n == A062756(n) (mod 2).

It is likely that a(136) = 1099528404993 is the last term.  The next term, if any, is greater than 10^200.

LINKS

Robert Israel, Table of n, a(n) for n = 1..136

EXAMPLE

a(4) = 49 = 110001_2 = 1211_3.

MAPLE

R:= NULL: count:= 0:

for a from 2 while count < 136 do

  for b from 1 to a-1  do

    p:= 2^a + 2^b + 1;

    if numboccur(1, convert(p, base, 3)) = 3 then

      count:= count+1;

      R:= R, p;

    fi

od od:

R;

CROSSREFS

Cf. A014311, A023694, A062756.  Contains A280997.

Sequence in context: A225131 A118361 A264908 * A088963 A301591 A301857

Adjacent sequences:  A281001 A281002 A281003 * A281005 A281006 A281007

KEYWORD

nonn,base

AUTHOR

Robert Israel, Jan 12 2017

STATUS

approved

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Last modified June 13 18:45 EDT 2021. Contains 345008 sequences. (Running on oeis4.)