A058012 - OEIS

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A058012

Consider the sequence {b(m)} of composite numbers (excluding 1); sequence gives values of b(m) where gcd(m, b(m)) increases.

4, 6, 10, 12, 14, 36, 39, 42, 45, 48, 124, 128, 132, 140, 345, 365, 370, 375, 380, 385, 390, 1086, 1140, 3101, 3122, 8416, 8480, 24309, 24318, 64550, 64560, 64570, 64590, 64600, 64660, 64730, 175208, 175219, 175230, 176616, 480876, 480888, 480948

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..43.

EXAMPLE

a(4) = 12 because twelve is the sixth composite number and gcd(6,12) > gcd(5,10).

MATHEMATICA

r=0; Do[a = GCD[n, n - PrimePi[n] -1]; If[a > r, r = a; Print[n]], {n, 1, 10^6} ]

CROSSREFS

Cf. A058011.

Sequence in context: A036438 A338519 A066190 * A026411 A020189 A166986