This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A000692 An approximation to population of x^2 + y^2. (Formerly M2311 N0913) 0
 1, 3, 4, 5, 9, 15, 27, 50, 92, 171, 322, 610, 1161, 2220, 4260, 8201, 15828, 30622, 59362, 115287, 224260, 436871, 852161, 1664196, 3253531, 6366973, 12471056, 24447507, 47962236, 94161474, 184983976, 363632192, 715220838, 1407510311 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS D. Hare, The constant c [Dave Hare, May 21 1996]. D. Shanks, The second-order term in the asymptotic expansion of B(x), Math. Comp., 18 (1964), 75-86. FORMULA a(n)=(b*2^n/sqrt(n*log(2)))*(1+c/(n*log(2))) where b=0.764223654... is the Landau-Ramanujan constant (A064533) and c=0.5819486593... is the second-order Landau-Ramanujan constant (A227158) given by c=(1/2)*(1-log(Pi*e^gamma/(2*L)))-(1/4)deriv(log(prod(1/(1-p^(-2*s)),p prime = 3(mod 4)),s=1) where L is the Lemniscate constant (A064853). - Sean A. Irvine, Feb 25 2011 CROSSREFS Cf. A000690, A064533. Sequence in context: A050161 A195609 A117125 * A195971 A080552 A215176 Adjacent sequences:  A000689 A000690 A000691 * A000693 A000694 A000695 KEYWORD nonn AUTHOR EXTENSIONS More terms from Sean A. Irvine, Feb 24 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 18 13:28 EDT 2018. Contains 313832 sequences. (Running on oeis4.)