A153091 Least k(n) such that k(n)*5^n*(5^n-1)+j is prime with j= -1 or 1 or both

1, 1, 3, 1, 6, 5, 5, 1, 2, 2, 18, 12, 12, 7, 1, 1, 4, 1, 9, 2, 36, 10, 70, 1, 3, 16, 6, 3, 2, 9, 74, 4, 6, 19, 20, 8, 14, 2, 2, 62, 3, 29, 47, 11, 47, 16, 58, 1, 49, 18, 51, 3, 12, 5, 18, 23, 1, 19, 54, 7, 35, 12, 7, 1, 12, 3, 5, 121, 70, 89, 12, 61, 33, 36, 9, 17, 135, 35, 21, 23, 20, 86, 18

Offset

1,3

Comments

when n increases sum k(n) for i=1 to n / sum n for i=1 to n tends to 13*log(5)/40 when n increases sum k(2*n+1) for i=1 to n / sum (2*n+1) for i=1 to n tends to log(5)/2.5 when n increases sum k(2*n) for i=1 to n / sum (2*n) for i=1 to n tends to log(5)/4

Links

Pierre CAMI, Table of n, a(n) for n = 1..1000

Example

1*5^1*(5^1-1)-1=19 prime so k(1)=1 1*5^2*(5^2-1)-1=599 prime as 601 so k(2)=1

Crossrefs

A152414, A152090, A152092, A152093, A152094, A152095

Sequence in context: A343062 A210602 A210801 * A210593 A179069 A235706

Adjacent sequences: A153088 A153089 A153090 * A153092 A153093 A153094

Keyword

nonn

Author

Pierre CAMI, Dec 18 2008

Status

approved