A171575 n-th noncomposite number plus n-th even nonprime number.

1, 6, 9, 13, 17, 23, 27, 33, 37, 43, 51, 55, 63, 69, 73, 79, 87, 95, 99, 107, 113, 117, 125, 131, 139, 149, 155, 159, 165, 169, 175, 191, 197, 205, 209, 221, 225, 233, 241, 247, 255, 263, 267, 279, 283, 289, 293, 307, 321, 327, 331, 337, 345, 349, 361, 369, 377

Offset

1,2

Links

Table of n, a(n) for n=1..57.

Formula

a(n) = A008578(n) + A163300(n).

Example

a(1) = 1 + 0 = 1, a(2) = 2 + 4 = 6, a(3) = 3 + 6 = 9.

Mathematica

Module[{nc=Select[Range[300], !CompositeQ[#]&], len}, len=Length[nc]; Join[ {1}, Rest[Total/@Thread[{nc, Range[2, 2len, 2]}]]]] (* Harvey P. Dale, Mar 08 2018 *)

Crossrefs

Cf. A008578(the noncomposite numbers), A163300(the even nonprime numbers).

Sequence in context: A236763 A030499 A181428 * A186524 A315963 A315964

Adjacent sequences: A171572 A171573 A171574 * A171576 A171577 A171578

Keyword

nonn

Author

Juri-Stepan Gerasimov, Dec 12 2009

Extensions

Entries checked by R. J. Mathar, May 23 2010

Status

approved