A140651 A140579^(-1) * A000290, the squares starting (1, 4, 9, ...).

1, 2, 3, 8, 5, 36, 7, 32, 27, 100, 11, 144, 13, 196, 225, 128, 17, 324, 19, 400, 441, 484, 23, 576, 125, 676, 243, 784, 29, 900, 31, 512, 1089, 1156, 1225, 1296, 37, 1444, 1521, 1600, 41, 1764, 43, 1936, 2025, 2116, 47, 2304, 343, 2500, 2601, 2704, 53, 2916, 3025, 3136, 3249, 3364, 59, 3600

Offset: 1

Author

Gary W. Adamson and Mats Granvik, May 20 2008

Keywords

• nonn

Comments

For n > 1, a(n) = n iff n is prime.

a(n) is n times the least common multiple of the proper divisors of n, a(n) = n*A048671(n). - Peter Luschny, Jun 22 2011

Examples

			A140579 = an infinite lower triangular matrix with A014963 in the main diagonal and the rest zeros; where A014963 = (1, 2, 3, 2, 5, 1, 7, ...).
a(5) = 5 = (1/A014963(5)) * 25 = (1/5)*25.
		

Crossrefs

Cf. A140579, A014963.

Programs

Maple

A140651  := n -> n*ilcm(op(numtheory[divisors](n) minus {1,n})); seq(A140651(i),i=1..60); # Peter Luschny, Jun 22 2011

Formula

A140579^(-1) * (1, 4, 9, 16, 25, ...).

Extensions

a(15)-a(60) from Peter Luschny, Jun 22 2011