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A039420 Numbers whose base-10 representation has the same nonzero number of 3's and 7's. 1
37, 73, 137, 173, 237, 273, 307, 317, 327, 347, 357, 367, 370, 371, 372, 374, 375, 376, 378, 379, 387, 397, 437, 473, 537, 573, 637, 673, 703, 713, 723, 730, 731, 732, 734, 735, 736, 738, 739, 743, 753, 763, 783, 793, 837, 873, 937, 973, 1037, 1073 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MAPLE
filter:= proc(n) local L;
L:= convert(n, base, 10);
has(L, 3) and numboccur(3, L) = numboccur(7, L)
end proc:
select(filter, [$1..5000]); # Robert Israel, Sep 24 2019
CROSSREFS
Sequence in context: A093838 A055604 A135952 * A043243 A044023 A179579
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved

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Last modified February 24 22:04 EST 2024. Contains 370307 sequences. (Running on oeis4.)