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

Offset: 1

Author

Robert G. Wilson v, Nov 13 2000

Keywords

• nonn

Examples

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

Crossrefs

Cf. A058011.

Programs

Mathematica

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

Extensions

Title corrected by Sean A. Irvine, Jul 17 2022