A054481 Highest common factor of successive highly composite numbers (1), A002182.

1, 2, 2, 6, 12, 12, 12, 12, 60, 60, 60, 120, 360, 120, 420, 420, 840, 2520, 2520, 2520, 5040, 5040, 5040, 2520, 2520, 5040, 5040, 27720, 27720, 55440, 55440, 55440, 55440, 166320, 55440, 110880, 55440, 360360, 360360

Offset: 2

Author

Henry Bottomley, Mar 31 2000

Keywords

• easy
• nonn

Comments

Not the same as the first differences of A002182. The latter are given by A262501, which differs from this sequence for the first time at n=25, where A262501(25) = 17640, while here the 25th term a(26) is 2520. The sequences differ next time at positions n = 52, 53, 54, 64, 67, 82, 83, 84, 85, 86, 87, 88, 90, 91, 96, 100, 106, ... (when one-based indexing as in A262501 is used). - Antti Karttunen, Sep 24 2015

Examples

			a(7)=12 because A002182(7)=36, A002182(6)=24 and GCD(36,24)=12.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 2..1000 (computed from the b-file of A002182 provided by _T. D. Noe_)

Crossrefs

Cf. A002182, A054482, A054483, A262501.

Formula

a(n) = GCD(A002182(n-1), A002182(n)) = A002182(n)/A054483(n) = A002182(n-1)/A054482(n).

Extensions

Erroneous comment (wrong interpretation) removed by Antti Karttunen, Sep 25 2015