A063649 - OEIS

This site is supported by donations to The OEIS Foundation.

A063649

Largest b such that 1/n=1/c+1/b has integer solutions with c>b.

3, 4, 6, 6, 10, 8, 12, 12, 15, 12, 21, 14, 21, 24, 24, 18, 30, 20, 36, 30, 33, 24, 42, 30, 39, 36, 44, 30, 55, 32, 48, 44, 51, 60, 63, 38, 57, 52, 72, 42, 78, 44, 66, 72, 69, 48, 84, 56, 75, 68, 78, 54, 90, 80, 105, 76, 87, 60, 110, 62, 93, 112, 96, 90, 110, 68, 102, 92, 120 (list; graph; refs; listen; history; internal format)

	OFFSET	`2,1`
	COMMENTS	`Smallest b is (n+1) since 1/n=1/(n(n+1))+1/(n+1)`
	FORMULA	`a(n) =n*A063648(n)/(A063648(n)-n) =2n-A063428(n).`
	EXAMPLE	`a(10)=15 since 1/10=1/20+1/20=1/30+1/15=1/35+1/14=1/60+1/12=1/110+1/11, but the first sum does not have c>b, leaving the second sum to provide the value.`
	CROSSREFS	`Cf. A018892, A063427, A063428, A063647, A063648.` `Sequence in context: A158907 A175708 A023830 * A053158 A185443 A158523` `Adjacent sequences: A063646 A063647 A063648 * A063650 A063651 A063652`
	KEYWORD	`nonn`
	AUTHOR	`Henry Bottomley (se16(AT)btinternet.com), Jul 23 2001`

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

Last modified February 17 19:13 EST 2012. Contains 206085 sequences.