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A086816 Smaller member of a twin prime pair with a triangular sum. 1

%I #8 Dec 15 2017 17:36:33

%S 17,59,137,149,1277,1619,2729,4127,6359,11717,13397,17489,20807,23027,

%T 28307,29669,51869,61379,69827,73847,78539,92567,97499,115769,138569,

%U 166667,176609,193379,200927,258317,304979,430007,500909,518759,536189

%N Smaller member of a twin prime pair with a triangular sum.

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

%H Harvey P. Dale, <a href="/A086816/b086816.txt">Table of n, a(n) for n = 0..300</a>

%e 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.

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

%Y Cf. A000217, A001359.

%K nonn

%O 0,1

%A _Jason Earls_, Aug 06 2003

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Last modified June 19 15:26 EDT 2024. Contains 373503 sequences. (Running on oeis4.)