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A014686
In sequence of prime numbers add 1 to first prime, 3rd prime, fifth prime, ... then subtract 1 from 2nd prime, fourth prime, sixth prime and so on.
7
3, 2, 6, 6, 12, 12, 18, 18, 24, 28, 32, 36, 42, 42, 48, 52, 60, 60, 68, 70, 74, 78, 84, 88, 98, 100, 104, 106, 110, 112, 128, 130, 138, 138, 150, 150, 158, 162, 168, 172, 180, 180, 192, 192, 198, 198, 212, 222, 228, 228, 234, 238, 242, 250, 258, 262, 270, 270
OFFSET
1,1
LINKS
FORMULA
a(n)=prime(n)-(-1)^n=A000040(n)-A033999(n+1). [From Juri-Stepan Gerasimov, Sep 11 2009]
MATHEMATICA
Module[{nn=60}, Total/@Partition[Riffle[Prime[Range[nn]], {1, -1}, {2, -1, 2}], 2]] (* Harvey P. Dale, Oct 04 2019 *)
CROSSREFS
Sequence in context: A096375 A062200 A114208 * A053090 A264400 A365660
KEYWORD
nonn,easy
EXTENSIONS
More terms from Andrew J. Gacek (andrew(AT)dgi.net)
STATUS
approved