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A086816 Smaller member of a twin prime pair with a triangular sum. 1
17, 59, 137, 149, 1277, 1619, 2729, 4127, 6359, 11717, 13397, 17489, 20807, 23027, 28307, 29669, 51869, 61379, 69827, 73847, 78539, 92567, 97499, 115769, 138569, 166667, 176609, 193379, 200927, 258317, 304979, 430007, 500909, 518759, 536189 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

It is easily shown that all terms end in 7 or 9.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..300

EXAMPLE

59 is a term because it is the smaller member of the twin prime pair (59,61) and 59 + 61 = 120 = 15*(15+1)/2.

MATHEMATICA

Transpose[Select[Partition[Prime[Range[45000]], 2, 1], #[[2]]-#[[1]]==2 && IntegerQ[(Sqrt[1+8Total[#]]-1)/2]&]][[1]] (* Harvey P. Dale, Dec 15 2011 *)

CROSSREFS

Cf. A000217, A001359.

Sequence in context: A104165 A031391 A176783 * A243096 A221569 A179816

Adjacent sequences:  A086813 A086814 A086815 * A086817 A086818 A086819

KEYWORD

nonn

AUTHOR

Jason Earls, Aug 06 2003

STATUS

approved

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Last modified January 22 04:27 EST 2020. Contains 331133 sequences. (Running on oeis4.)