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A085645 Smallest number having n divisors ending with 1 or 9. 0
1, 9, 63, 99, 441, 693, 5103, 1881, 5733, 4851, 35721, 9009, 194481, 56133, 51597, 27027 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The sequence continues ?, 63063, ?, 81081, ?, 392931, ?, 153153,... - R. J. Mathar, Oct 18 2013

LINKS

Table of n, a(n) for n=1..16.

A. Stenger, An Excess of Divisors

Wikipedia, Table of divisors

EXAMPLE

The divisors of 63 are 1, 3, 7, 9, 21 and 63. Three of them end either in 1 or 9. No smaller number satisfies this condition, so a(3) = 63

MATHEMATICA

tbl=Table[Length[Select[IntegerDigits/@Divisors[i], Last[ # ]==1||Last[ # ]==9&]], {i, 50000}]; Table[First[Position[tbl, i]], {i, 12}]//Flatten

CROSSREFS

Sequence in context: A181403 A292309 A285456 * A299579 A269641 A269410

Adjacent sequences:  A085642 A085643 A085644 * A085646 A085647 A085648

KEYWORD

base,nonn

AUTHOR

Lekraj Beedassy, Jul 11 2003

EXTENSIONS

Corrected and extended by Harvey P. Dale, Jul 18 2003

STATUS

approved

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Last modified November 22 13:47 EST 2019. Contains 329393 sequences. (Running on oeis4.)