

A117313


Average of twinprime pairs for pairs that are expressible as the sum of two triangular numbers.


1



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
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..40.


EXAMPLE

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.


MATHEMATICA

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, Apr 27 2006


CROSSREFS

Cf. A001097, A117048, A117112.
Sequence in context: A286659 A320483 A260417 * A080563 A221520 A214311
Adjacent sequences: A117310 A117311 A117312 * A117314 A117315 A117316


KEYWORD

easy,nonn


AUTHOR

Greg Huber, Apr 24 2006


EXTENSIONS

More terms from Robert G. Wilson v, Apr 27 2006


STATUS

approved



