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A090548 Least number that ends an arithmetic progression of n numbers with the same number of divisors. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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.

LINKS

Table of n, a(n) for n=1..25.

FORMULA

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

EXAMPLE

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.

Sequence in context: A139513 A144593 A057191 * A087309 A127781 A271918

Adjacent sequences:  A090545 A090546 A090547 * A090549 A090550 A090551

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Dec 09 2003

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

STATUS

approved

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Last modified March 2 19:18 EST 2021. Contains 341756 sequences. (Running on oeis4.)