A090548 Least number that ends an arithmetic progression of n numbers with the same number of divisors.

1, 3, 7, 23, 29, 157, 215, 1139, 1211, 2089, 5161, 5293, 6347, 10717, 14233, 28213, 31451, 72965, 119029, 121603, 124177, 611261, 632171, 2003171, 2012771

Offset: 1

Author

Amarnath Murthy, Dec 09 2003

Keywords

• nonn

Comments

In the following triangle the n-th row contains the least set of n numbers in arithmetic progression with the same number of divisors. By "least" we mean that the largest term is minimized. Sequence contains the leading diagonal. In other words, largest of n numbers in arithmetic progression with the same tau function, or 0 if no such number exists.

Examples

			Triangle (A113470) begins:
1
2 3
3 5 7
5 11 17 23
5 11 17 23 29 ...
		

Crossrefs

Leading diagonal of A113470.

Cf. A087309, A096003, A113470, A087308, A090547, A090549.

Formula

a(n)=A090547(n)+(n-1)*A090549(n). - R. J. Mathar, Apr 28 2007

Extensions

Corrected and extended by R. J. Mathar, Apr 28 2007

More terms from David Wasserman, Jan 08 2006, May 11 2007

Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, May 11 2007