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Search: id:A125130
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| A125130 |
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Successive sums of consecutive primes that form a triangular grid. |
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+0
1
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| 2, 10, 41, 129, 328, 712, 1371, 2427, 4028, 6338, 9523, 13887, 19580, 26940, 36227, 47721, 61910, 79168, 99685, 124211, 153178, 186914, 225831, 271061, 322858, 382038, 448869, 524451, 608914, 704204, 810459, 927883, 1057828, 1201162
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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These sums, for a given n, can be estimated by the following formula. sum est = x^2/(2*log(x)-1) Where x = prime(n*(n-1)/2+n) For example, n = 10000 x = 982555543 sum est = 23889718028585418 sum act = 23904330028803899 Relative Error = 0.00061127001680771897
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EXAMPLE
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The consecutive primes 2,3,5,7,11,13 form the triangular grid,
....... 2
..... 3 5
... 7 11 13
These consecutive primes add up to 41, the third entry in the table.
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PROGRAM
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(PARI) g2(n) = for(j=1, n, y=g(j*(j+1)/2); print1(y", ")) g(n) = local(s=0, x); for(x=1, n, s+=prime(x)); s
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CROSSREFS
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Cf. A078721.
Sequence in context: A080252 A127113 A051540 this_sequence A110684 A037561 A135512
Adjacent sequences: A125127 A125128 A125129 this_sequence A125131 A125132 A125133
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KEYWORD
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easy,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)hotmail.com), Jan 10 2007
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