OFFSET
1,2
COMMENTS
This sequence is matched with another auxiliary sequence called c(n) (A190894). Rowland's sequence (A106108) can be easily described in terms of c(n) and r(n). Also, they can be used to prove easily that the difference between two consecutive terms is always 1 or a prime.
This sequence is related to Rowland's sequence (A106108) with initial condition a(1)=7.
Sequence r(n) satisfies 2r(n) - 1 = c(n), for any n>1.
For further information, see the references.
LINKS
F. Chamizo, D. Raboso, and S. Ruiz-Cabello, On Rowland's sequence, Electronic J. Combin., Vol. 18(2), 2011, #P10.
E. S. Rowland, A natural prime-generating recurrence, J. Integer Seq., 11(2): Article 08.2.8, 13, 2008.
EXAMPLE
For n = 2, r(2) = 1/2 * (c(2) + 1) = 1/2 * (9 + 1) = 5.
For n = 3, r(3) = 1/2 * (c(3) + 1) = 1/2 * (11 + 1) = 6.
CROSSREFS
KEYWORD
nonn
AUTHOR
Serafín Ruiz-Cabello, May 23 2011
STATUS
approved