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A014687 In sequence of odd primes add 1 to first prime, 3rd prime, 5th prime, ... then subtract 1 from 2nd prime, fourth prime, sixth prime and so on. 9
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..58.

FORMULA

Also a(n) = prime(n+1)+(-1)^(n+1). - Juri-Stepan Gerasimov, Sep 10 2009

Or, a(n) = odd prime(n)-(-1)^n. - Juri-Stepan Gerasimov, Sep 10 2009

a(n)+a(n-1) = prime(n)+prime(n+1) i.e. a(n) = prime(n)+prime(n+1)-a(n-1) generates sequence with initial value a(1)=4. - Labos Elemer, Apr 24 2003; corrected by Dean Hickerson, Apr 27 2003

a(n) = A000040(n+1)-A033999(n+1). - Juri-Stepan Gerasimov, Sep 10 2009

EXAMPLE

a(4)+a(3) = 10+8 = 18 = prime(4)+prime(5) = 7+11.

MATHEMATICA

a[1]=4; a[n_] := a[n]=Prime[n]+Prime[n+1]-a[n-1]

Total/@Partition[Riffle[Prime[Range[2, 60]], {1, -1}], 2] (* Harvey P. Dale, May 19 2011 *)

CROSSREFS

Sequence in context: A093340 A046558 A180854 * A172022 A152967 A301705

Adjacent sequences:  A014684 A014685 A014686 * A014688 A014689 A014690

KEYWORD

nonn,easy

AUTHOR

Mohammad K. Azarian

EXTENSIONS

More terms from Erich Friedman.

STATUS

approved

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Last modified November 20 05:07 EST 2019. Contains 329323 sequences. (Running on oeis4.)