id:A123674 - OEIS Search Results

Search: id:A123674

Displaying 1-1 of 1 results found.

page 1

a(n) = number of primes of the form 2^n - 3^k.

+0
1

0, 1, 2, 2, 4, 2, 3, 2, 4, 2, 2, 2, 3, 3, 1, 2, 4, 0, 3, 4, 4, 3, 3, 3, 0, 1, 1, 0, 2, 1, 1, 1, 3, 2, 3, 2, 2, 0, 1, 2, 2, 3, 0, 0, 4, 4, 3, 2, 5, 4, 4, 0, 0, 0, 1, 1, 4, 5, 2, 4, 3, 3, 0, 1, 1, 2, 5, 0, 1, 1, 4, 3, 1, 0, 1, 1, 3, 2, 3, 0, 2, 4, 2, 1, 2, 2, 3, 0, 7, 2, 4, 4, 2, 2, 2, 3, 5, 0, 3, 1, 1, 1, 3, 3, 2 (list; graph; listen)

	OFFSET	`1,3`
	COMMENT	`a(1) = 0 because there are no prime numbers of the form 2^1 - 3^k. a(2) = 1 because the only prime of the form 2^2 - 3^k is 2^2 - 3^0 = 3. a(3) = because there are two primes of the form 2^3 - 3^k: 2^3 - 3^0 = 7 and 2^3 - 3^1 = 5.`
	MATHEMATICA	`Table[Length[Select[Range[0, Floor[Log[3, 2^n]]], PrimeQ[2^n-3^# ]&]], {n, 1, 200}]`
	CROSSREFS	`Sequence in context: A127796 A131287 A102640 this_sequence A092607 A057939 A061338` `Adjacent sequences: A123671 A123672 A123673 this_sequence A123675 A123676 A123677`
	KEYWORD	`nonn`
	AUTHOR	`Alexander Adamchuk (alex(AT)kolmogorov.com), Nov 17 2006`

page 1

Search completed in 0.002 seconds

Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.

AT&T Labs Research