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A044993
Numbers whose base-3 representation contains no 0's and exactly four 2's.
1
80, 161, 215, 233, 239, 241, 404, 458, 476, 482, 484, 620, 638, 644, 646, 692, 698, 700, 716, 718, 724, 1133, 1187, 1205, 1211, 1213, 1349, 1367, 1373, 1375, 1421, 1427, 1429, 1445, 1447, 1453, 1835, 1853, 1859, 1861, 1907
OFFSET
1,1
COMMENTS
a(A000389(k)) = (161*3^(k-5)-1)/2 for k >= 5. - Robert Israel, Sep 21 2020
LINKS
MAPLE
f:= proc(d) local C, c;
C:= combinat:-choose(d, 4);
c:=(3^(d)-1)/2;
op(sort([seq(c+add(3^(i-1), i=t), t=C)]))
end proc:
seq(f(d), d=4..8); # Robert Israel, Sep 21 2020
MATHEMATICA
A044993list[upto_]:=Select[Range[upto], DigitCount[#, 3, 0]==0&&DigitCount[#, 3, 2]==4&]; A044993list[3000] (* Paolo Xausa, Aug 03 2023 *)
CROSSREFS
Sequence in context: A043332 A023702 A031460 * A043486 A031496 A044331
KEYWORD
nonn,base
STATUS
approved