

A129752


Triangular numbers t which are average of two consecutive primes p and p+4.


3



15, 21, 45, 105, 231, 351, 465, 741, 861, 1431, 1485, 3081, 3321, 4005, 7875, 10731, 11175, 11781, 13695, 14535, 17205, 17391, 18915, 21321, 22155, 23871, 30135, 33411, 36585, 39621, 42195, 51681, 58311, 80601, 90525, 92235, 97461, 108345
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OFFSET

1,1


COMMENTS

All terms are multiples of 3.


LINKS

Table of n, a(n) for n=1..38.


FORMULA

t/+2 are pair of consecutive primes.


EXAMPLE

15/+2=(13,17), 21/+2=(19,23), 45/+2=(43,47) are pairs of consecutive primes.


CROSSREFS

Cf. A000217, A024675, A130178.
Sequence in context: A331628 A171569 A247021 * A015831 A275169 A063176
Adjacent sequences: A129749 A129750 A129751 * A129753 A129754 A129755


KEYWORD

nonn


AUTHOR

Zak Seidov, May 14 2007


STATUS

approved



