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Search: id:A101306
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| A101306 |
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a(n) = sum_{i=1..n} {last digit of prime(i)}. |
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+0
3
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| 2, 5, 10, 17, 18, 21, 28, 37, 40, 49, 50, 57, 58, 61, 68, 71, 80, 81, 88, 89, 92, 101, 104, 113, 120, 121, 124, 131, 140, 143, 150, 151, 158, 167, 176, 177, 184, 187, 194, 197, 206, 207, 208, 211, 218, 227, 228, 231, 238, 247, 250, 259, 260, 261, 268, 271, 280
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Asymptotically, a(n) ~ 5n by Dirichlet's theorem. [From Charles R Greathouse IV, Sep 28 2008]
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FORMULA
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Partial sums of A007652.
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EXAMPLE
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a(1)=2
a(2)=2+3
a(3)=2+3+5
a(4)=2+3+5+7
a(5)=2+3+5+7+1(1)= 2+3+5+7+1
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MATHEMATICA
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f[n_] := Sum[ Mod[ Prime[i], 10], {i, n}]; Table[ f[n], {n, 60}] (from Robert G. Wilson v Dec 22 2004)
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PROGRAM
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(PARI) sum(k=1, n, prime(k)%10) [From Charles R Greathouse IV, Sep 28 2008]
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CROSSREFS
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Sequence in context: A079984 A027613 A067112 this_sequence A051351 A111925 A030723
Adjacent sequences: A101303 A101304 A101305 this_sequence A101307 A101308 A101309
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KEYWORD
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nonn,base,easy
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AUTHOR
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Jorge Coveiro (jorgecoveiro(AT)yahoo.com), Dec 22 2004
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EXTENSIONS
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Corrected and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 22 2004
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