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A182695
a(n) = the smallest 4-digit number with exactly n divisors, a(n) = 0 if no such number exists.
1
0, 1009, 1369, 1003, 2401, 1004, 0, 1001, 1089, 1053, 1024, 1012, 4096, 1088, 1936, 1000, 0, 1044, 0, 1040, 1600, 3072, 0, 1020, 1296, 0, 1764, 1344, 0, 1008, 0, 1080, 9216, 0, 5184, 1260, 0, 0, 0, 1680, 0, 2880, 0, 0, 3600, 0, 0, 2520, 0, 6480
OFFSET
1,2
FORMULA
A000005(a(n)) = n for a(n) > 0.
64 = max n such that a(n) > 0, a(n) = 0 for n > 64.
a(n) <= A182696(n).
MATHEMATICA
digits=4; tbl=DivisorSigma[0, Range[10^(digits-1), 10^digits-1]]; t=Table[0, {Max[tbl]}]; offset=10^digits; Do[t[[tbl[[-i]]]]=offset-i, {i, Length[tbl]}]; t
CROSSREFS
Cf. A182696.
Sequence in context: A325090 A024974 A025400 * A100776 A126238 A176930
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Nov 27 2010
STATUS
approved