A000001 Sophie Germain triangular numbers

[zak seidov]

Just submitted:

%I A000001
%S A000001
0,1,10,45,351,1540,11935,52326,405450,1777555,13773376,60384555,467889345,2051297326,15894464365,69683724540,539943899076,2367195337045,18342198104230
%N A000001 Sophie Germain triangular numbers tr:
2*tr+1 is also a triangular number.
%C A000001 a(n)=(A124124[[n]]^2+A124124[[n]]-2)/4.
%F A000001 For given a(1..6),
a(n)=35(a(n-2)-a(n-4))+a(n-6).
%Y A000001 Cf. A005384,  A077442, A124124.


 
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