A051999 Minimal value w such that A051953(w) = w - phi(w) is prime and w has n prime divisors.

4, 15, 255, 5865, 170085, 5437705, 226473065, 10380578845, 494390700895, 43592479037107

Offset

1,1

Comments

a(11) <= 2995513256722805. - Donovan Johnson, Feb 06 2010

Links

Table of n, a(n) for n=1..10.

Example

a(1)=2^2, a(2)=3*5, a(3)=3*5*17, a(4)=3*5*17*23, a(5)=3*5*17*23*29, a(6)=5437705=5*7*13*17*19*37 with 1,2,3,4,5,6 prime divisors, respectively. The generated primes of form w - phi(w) are as follows: 2, 7, 127, 3049, 91237, 2452721.

Crossrefs

Cf. A050530, A051953.

Sequence in context: A139244 A369727 A090115 * A048731 A363351 A000881

Adjacent sequences: A051996 A051997 A051998 * A052000 A052001 A052002

Keyword

nonn,more

Author

Labos Elemer, Jan 05 2000

Extensions

a(7)-a(10) from Donovan Johnson, Feb 06 2010

Status

approved