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Search: id:A117313
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| A117313 |
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Average of twin-prime pairs for pairs that are expressible as the sum of two triangular numbers. |
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+0
2
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| 12, 30, 138, 192, 462, 660, 822, 1092, 1722, 2028, 2082, 2712, 3360, 3540, 3918, 6132, 6762, 7590, 7878, 7950, 8220, 9462, 9858, 11352, 12108, 12378, 13692, 13998, 14448, 16140, 16230, 17292, 17418, 17580, 18912, 19470, 19542, 19992, 20550, 20748
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(1) = 12 as witnessed by 11 = 1 + 10 and 13 = 3 + 10;
a(5) = 462 as witnessed by 461 = 55 + 406 and 463 = 28 + 435.
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MATHEMATICA
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s = Select[Union@ Flatten@ Table[i(i + 1)/2 + j(j + 1)/2, {i, 200}, {j, 0, i}], PrimeQ@ # &]; t = Select[Range@ Length@s - 1, s[[ # ]] + 2 == s[[ # + 1]] &]; s[[t]] + 1 - Robert G. Wilson v (rgwv(at)rgwv.com), Apr 27 2006
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CROSSREFS
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Cf. A001097, A117048, A117112.
Sequence in context: A064483 A110019 A069486 this_sequence A080563 A005147 A007308
Adjacent sequences: A117310 A117311 A117312 this_sequence A117314 A117315 A117316
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KEYWORD
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easy,nonn
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AUTHOR
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Greg Huber (huber(AT)alum.mit.edu), Apr 24 2006
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(at)rgwv.com), Apr 27 2006
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