id:A138586 - OEIS Search Results

Search: id:A138586

Displaying 1-1 of 1 results found.

page 1

a(1) = 1; a(n) = a(n-1) + (n!)^7.

+0
1

1, 129, 280065, 4586751489, 358322666751489, 100306488365546751489, 82606511560391889386751489, 173238283180457843219993066751489, 828593116199250458889895450218986751489 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`After a(1) = 1 these are all divisible by 3. a(n)/3 is prime (i.e. a(n) is semiprime) for n = 2, 4 (i.e. (1!)^7 + (2!)^7 + (3!)^7 + (4!)^7 = 4586751489 = 3 * 1528917163) and then when next?`
	FORMULA	`a(n) = SUM{k=1..n] (k!)^7 = SUM[k=1..n] A001015(A000142(n)).`
	CROSSREFS	`Cf. A000142, A001015, A104344, A100288.` `Sequence in context: A000541 A023876 A143006 this_sequence A103347 A113489 A043604` `Adjacent sequences: A138583 A138584 A138585 this_sequence A138587 A138588 A138589`
	KEYWORD	`easy,nonn`
	AUTHOR	`Jonathan Vos Post (jvospost3(AT)gmail.com), May 18 2008`

page 1

Search completed in 0.002 seconds

Last modified November 29 12:46 EST 2009. Contains 167659 sequences.

AT&T Labs Research