A175028 a(n)=n+1 if n is prime, otherwise a(n)=n-1.

0, 3, 4, 3, 6, 5, 8, 7, 8, 9, 12, 11, 14, 13, 14, 15, 18, 17, 20, 19, 20, 21, 24, 23, 24, 25, 26, 27, 30, 29, 32, 31, 32, 33, 34, 35, 38, 37, 38, 39, 42, 41, 44, 43, 44, 45, 48, 47, 48, 49, 50, 51, 54, 53, 54, 55, 56, 57, 60, 59, 62, 61, 62, 63, 64, 65, 68, 67, 68, 69, 72, 71, 74

Offset

1,2

Links

Table of n, a(n) for n=1..73.

Mathematica

Table[If[PrimeQ[n], n+1, n-1], {n, 1, 200}]

Crossrefs

Cf. A068519, A167480, A167482, A175027.

Sequence in context: A097857 A176058 A110738 * A248006 A197699 A005092

Adjacent sequences: A175025 A175026 A175027 * A175029 A175030 A175031

Keyword

nonn

Author

Zak Seidov, Nov 04 2009

Status

approved