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A051353
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a(n) = a(n-1) + n^2 if n prime else a(n-1) - n.
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1
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0, -1, 3, 12, 8, 33, 27, 76, 68, 59, 49, 170, 158, 327, 313, 298, 282, 571, 553, 914, 894, 873, 851, 1380, 1356, 1331, 1305, 1278, 1250, 2091, 2061, 3022, 2990, 2957, 2923, 2888, 2852, 4221, 4183, 4144, 4104, 5785, 5743, 7592, 7548
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text;
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OFFSET
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0,3
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LINKS
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FORMULA
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MATHEMATICA
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nxt[{n_, a_}]:={n+1, If[PrimeQ[n+1], a+(n+1)^2, a-(n+1)]}; Transpose[ NestList[ nxt, {0, 0}, 50]][[2]] (* Harvey P. Dale, Dec 12 2012 *)
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PROG
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(Haskell)
a051353 n = a051353_list !! n
a051353_list = 0 : zipWith (+) a051353_list
(zipWith (\chi x -> x * (chi * (x + 1) - 1)) a010051_list [1..])
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CROSSREFS
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KEYWORD
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sign,easy,nice
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AUTHOR
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Armand Turpel armandt(AT)unforgettable.com
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STATUS
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approved
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