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A085090
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Starting with n+(n-1) go on adding n-2, then n-3, etc. until one gets a prime; a(n) = smallest prime in n+(n-1)+(n-2)+...+(n-i) (with the least i that gives a prime), or 0 if no such prime exists.
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3
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0, 3, 5, 7, 0, 11, 13, 0, 17, 19, 0, 23, 0, 0, 29, 31, 0, 0, 37, 0, 41, 43, 0, 47, 0, 0, 53, 0, 0, 59, 61, 0, 0, 67, 0, 71, 73, 0, 0, 79, 0, 83, 0, 0, 89, 0, 0, 0, 97, 0, 101, 103, 0, 107, 109, 0, 113, 0, 0, 0, 0, 0, 0, 127, 0, 131, 0, 0, 137, 139, 0, 0, 0, 0, 149, 151, 0, 0, 157, 0, 0, 163
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| If 2n-1 is prime then a(n) = 2n-1, otherwise a(n) = 0. - David Wasserman (wasserma(AT)spawar.navy.mil), Jan 25 2005
a(A098090(n)-1)=2*A098090(n)-3; a(n)=(2*n-1)*A101264(n-1). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Sep 14 2006
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EXAMPLE
| a(8) = 0 as there is no prime in the partial sum of the finite sequence 8,7,6,5,4,3,2,1.
a(7) = 13 = 7 + 6.
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CROSSREFS
| Cf. A122845.
Sequence in context: A099744 A024601 A173013 * A084713 A162538 A084712
Adjacent sequences: A085087 A085088 A085089 * A085091 A085092 A085093
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KEYWORD
| easy,nonn
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AUTHOR
| Amarnath Murthy and Meenakshi Srikanth (amarnath_murthy(AT)yahoo.com), Jul 02 2003
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EXTENSIONS
| More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Jan 25 2005
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