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A129545 Triangular numbers T such that T+1 is a prime. 3
1, 6, 10, 28, 36, 66, 78, 136, 190, 210, 276, 378, 630, 820, 946, 990, 1128, 1326, 1596, 1830, 2016, 2080, 2346, 2556, 2850, 2926, 3570, 3916, 4560, 4656, 4950, 5050, 5778, 6216, 6328, 8646, 8778, 9180, 9870, 11026, 12720, 13366, 14028, 14196, 14878 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

The only triangular numbers T such that T-1 is a (positive) prime are 3 and 6.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A000217(A067186(n)) . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Dec 10 2007

MATHEMATICA

Select[Accumulate[Range[200]], PrimeQ[#+1]&] (* From Harvey P. Dale, Nov 08 2011 *)

CROSSREFS

Cf. A000217, A129755, A130178.

Sequence in context: A081394 A184387 A014494 * A097578 A103767 A025129

Adjacent sequences:  A129542 A129543 A129544 * A129546 A129547 A129548

KEYWORD

nonn

AUTHOR

Zak Seidov (zakseidov(AT)yahoo.com), May 30 2007

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Last modified February 17 14:50 EST 2012. Contains 206050 sequences.