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A219095 Numbers k such that if b/c > 1 is the least reduced fraction using divisors b and c of k, then c > 1. 4
6, 12, 15, 18, 20, 21, 24, 28, 30, 35, 36, 40, 42, 45, 48, 54, 55, 56, 60, 63, 65, 66, 70, 72, 75, 77, 78, 80, 84, 85, 88, 90, 91, 95, 96, 99, 100, 102, 104, 105, 108, 110, 112, 114, 115, 117, 119, 120, 126, 130, 132, 133, 135, 138, 140, 143, 144, 147, 150 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Clark Kimberling, Table of n, a(n) for n = 2..5066

EXAMPLE

For n = 2,...,12, the fractions are 2/1, 3/1, 2/1, 5/1, 3/2, 7/1, 2/1, 3/1, 2/1, 11/1, 4/3, so that

A218993 = (2, 3, 2, 5, 3, 7, 2, 3, 2, 11, 4, ... );

A219093 = (1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 3, ... );

A219094 = (1, 1, 2, 1, 1, 1, 4, 3, 5, 1, 1, ... );

A219095 = (6, 12, 15, 18, 20, 21, 24, 28, 30, 35, 36, ... ).

The least k for which A219093(k) > 1 is 6, so that a(2) = 6; the next such k is 12, so that a(3) = 12, etc.

MATHEMATICA

(See A218993.)

CROSSREFS

Cf. A218993, A219093, A219095.

Sequence in context: A175952 A278638 A208770 * A107487 A092671 A005279

Adjacent sequences:  A219092 A219093 A219094 * A219096 A219097 A219098

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Feb 06 2013

STATUS

approved

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Last modified June 17 05:53 EDT 2021. Contains 345080 sequences. (Running on oeis4.)