id:A063440 - OEIS Search Results

Search: id:A063440

Displaying 1-1 of 1 results found.

page 1

Number of divisors of n-th triangular number.

+0
4

1, 2, 4, 4, 4, 4, 6, 9, 6, 4, 8, 8, 4, 8, 16, 8, 6, 6, 8, 16, 8, 4, 12, 18, 6, 8, 16, 8, 8, 8, 10, 20, 8, 8, 24, 12, 4, 8, 24, 12, 8, 8, 8, 24, 12, 4, 16, 24, 9, 12, 16, 8, 8, 16, 24, 24, 8, 4, 16, 16, 4, 12, 36, 24, 16, 8, 8, 16, 16, 8, 18, 18, 4, 12, 24, 16, 16, 8, 16, 40, 10, 4, 16 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Ray Chandler, Table of n, a(n) for n=1..10000`
	FORMULA	`a(n) = A000005(A000217(n))`
	EXAMPLE	`a(6) = 4 since 1+2+3+4+5+6 = 21 has four divisors {1,3,7,21}.`
	CROSSREFS	`a(n) = 4 iff either n is in A005383 or n/2 is in A005384. a(n) is odd iff n is in A001108.` `Sequence in context: A035661 A046930 A035645 this_sequence A008497 A108039 A097154` `Adjacent sequences: A063437 A063438 A063439 this_sequence A063441 A063442 A063443`
	KEYWORD	`nonn`
	AUTHOR	`Henry Bottomley (se16(AT)btinternet.com), Jul 24 2001`

page 1

Search completed in 0.002 seconds

Last modified September 6 16:04 EDT 2008. Contains 143483 sequences.

AT&T Labs Research