A069531 - OEIS

This site is supported by donations to The OEIS Foundation.

A069531

Smallest positive k such that 10^k + 1 is divisible by n, or 0 if no such number exists.

1, 0, 0, 0, 0, 0, 3, 0, 0, 0, 1, 0, 3, 0, 0, 0, 8, 0, 9, 0, 0, 0, 11, 0, 0, 0, 0, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 23, 0, 21, 0, 0, 0, 0, 0, 0, 0, 0, 0, 29, 0, 30, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 22, 0, 3, 0, 0, 0, 0, 0, 48, 0, 0, 0, 2 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,7`
	COMMENTS	`a(n)(<>0) is a divisor of phi(n). If n is a prime with primitive root 10 (cf. A001913) then a(n) = (n-1)/2.`
	EXAMPLE	`a(7) = a(13) = 3 as 1001 is divisible by 7 and 13. a(17) = 8 as 17 divides 100000001 = 10^8 + 1.`
	CROSSREFS	`Cf. A069521 to A069530.` `Cf. A000010, A001913, A002329.` `Sequence in context: A096693 A193139 A083206 * A035677 A143276 A101941` `Adjacent sequences: A069528 A069529 A069530 * A069532 A069533 A069534`
	KEYWORD	`nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 01 2002`
	EXTENSIONS	`More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 03 2002`

Content is available under The OEIS End-User License Agreement .

Last modified February 13 08:12 EST 2012. Contains 205451 sequences.