A172022 a(n) = prime(n) + (-1)^n.

1, 4, 4, 8, 10, 14, 16, 20, 22, 30, 30, 38, 40, 44, 46, 54, 58, 62, 66, 72, 72, 80, 82, 90, 96, 102, 102, 108, 108, 114, 126, 132, 136, 140, 148, 152, 156, 164, 166, 174, 178, 182, 190, 194, 196, 200, 210, 224, 226, 230, 232, 240, 240, 252, 256, 264, 268, 272, 276

Offset

1,2

Comments

1 together with A014687.

Links

Table of n, a(n) for n=1..59.

Formula

a(n+1) = A014687(n).

Example

a(1) = prime(1) + (-1)^1 = 2 - 1 = 1.

Maple

A172022:=n->ithprime(n)+(-1)^n: seq(A172022(n), n=1..100); # Wesley Ivan Hurt, Jan 09 2017

Mathematica

upto=300; Total/@Partition[Riffle[Prime[Range[PrimePi[upto]]], {-1, 1}], 2] (* Harvey P. Dale, May 12 2011 *)
Table[Prime@ n + (-1)^n, {n, 59}] (* Michael De Vlieger, Jan 10 2017 *)

Prog

(PARI) a(n)=prime(n)+(-1)^n \\ Charles R Greathouse IV, May 12 2011
(PARI) k=1; forprime(p=2, 300, print1(p+(k*=-1)", ")) \\ Charles R Greathouse IV, May 25 2011
(Magma) [NthPrime(n) + (-1)^n: n in [1..60]]; // Vincenzo Librandi, Feb 13 2015

Crossrefs

Cf. A000040, A014687.

Sequence in context: A046558 A180854 A014687 * A152967 A376433 A301705

Adjacent sequences: A172019 A172020 A172021 * A172023 A172024 A172025

Keyword

nonn,easy

Author

Juri-Stepan Gerasimov, Jan 22 2010

Extensions

Entries checked by D. S. McNeil, Dec 01 2010

Status

approved