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A195548
Numerators b(n) of Pythagorean approximations b(n)/a(n) to 1/2.
3
0, 3, 5, 8, 39, 105, 136, 715, 1869, 2448, 12815, 33553, 43920, 229971, 602069, 788120, 4126647, 10803705, 14142232, 74049691, 193864605, 253772064, 1328767775, 3478759201, 4553754912, 23843770275, 62423800997, 81713816360, 427859097159, 1120149658761
OFFSET
1,2
COMMENTS
See A195500 for discussion and list of related sequences; see A195547 for Mathematica program.
FORMULA
a(n) = (F(n+1)^2-F(n)^2)/(2-((n+2)^2 mod 3)), where F(n)=Fibonacci(n). [Gary Detlefs, Oct 15 2011]
Empirical G.f.: x*(3+5*x+8*x^2-12*x^3+20*x^4+x^6-x^7)/(1-17*x^3-17*x^6+x^9). [Colin Barker, Apr 15 2012]
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Sep 20 2011
STATUS
approved