id:A109200 - OEIS Search Results

Search: id:A109200

Displaying 1-1 of 1 results found.

page 1

Minimal value of k>0 such that n^5 + k^2 is a semiprime.

+0
7

2, 3, 1, 2, 7, 3, 5, 16, 3, 4, 1, 10, 1, 2, 3, 8, 1, 2, 5, 10, 3, 2, 1, 8, 5, 4, 9, 2, 9, 3, 13, 8, 15, 8, 7, 2, 5, 2, 3, 16, 3, 9, 31, 14, 3, 4, 9, 10, 11, 2, 3, 2, 9, 12, 5, 4, 3, 10, 5, 6, 11, 6, 9, 16, 5, 28, 19, 4, 3, 16, 3, 6, 7, 4, 9, 28, 9, 6, 11, 12, 7, 10, 7, 14, 29, 3, 11, 8, 3, 18, 7, 8, 3, 4 (list; graph; listen)

	OFFSET	`0,1`
	FORMULA	`a(n) = minimal value of k>0 such that n^5 + k^2 is a semiprime.`
	EXAMPLE	`a(0) = 2 because 0^5 + 1^2 = 1 is not semiprime, but 0^5 + 2^2 = 4 = 2^2 is.` `a(1) = 3 because 1^5 + 1^2 and 1^5 + 2^2 are not semiprime, but 1^5 + 3^2 = 10 = 2 * 5 is semiprime.` `a(2) = 1 because 2^5 + 1^2 = 33 = 3 * 11 is semiprime.` `a(42) = 31 because 42^5 + 31^2 = 130692193 = 571 * 228883 and for no smaller k>0 is 42^4 + k^2 a semiprime.`
	CROSSREFS	`Cf. A001358, A108714, A109197, A109198, A109199.` `Sequence in context: A154948 A109091 A138507 this_sequence A158909 A101477 A077887` `Adjacent sequences: A109197 A109198 A109199 this_sequence A109201 A109202 A109203`
	KEYWORD	`easy,nonn`
	AUTHOR	`Jonathan Vos Post (jvospost3(AT)gmail.com), Jun 26 2005`

page 1

Search completed in 0.002 seconds

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

AT&T Labs Research