A228115 First differences of A227693.

3, 21, 143, 1061, 8366, 68932, 585881, 5094722, 45074595, 404185377, 3663479699, 33498077106, 308548877876, 2859703657128, 26646019345842, 249434445759050, 2344494354096166, 22116172789221197, 209301155352811190, 1986521422431963549, 18904049485198437478, 180323870540071281301, 1723847795281971132487, 16512536418951055856540, 158463448213030472998711

Offset

1,1

Comments

This sequence gives a good approximation of the number of primes with n digits (A006879); see (A228116).

References

John H. Conway and R. K. Guy, The Book of Numbers, Copernicus, an imprint of Springer-Verlag, NY, 1996, page 144.

Links

Vladimir Pletser, Table of n, a(n) for n = 1..500

Eric Weisstein's World of Mathematics, Fibonacci Polynomial.

Formula

a(n)= A227693(n)- A227693(n-1)

Example

For n =1, A227693(1)- A227693(0) =4-1=3, where A227693(1)= round((F[3]( 1.016825…))^2)=4 with F[3](x) = x^2+1 and A227693(0)= round(F[1](x)) =1 with F[1](x)=1

Crossrefs

Cf. A006879, A228111 - A228116

Sequence in context: A337467 A318041 A054419 * A033888 A141492 A243397

Adjacent sequences: A228112 A228113 A228114 * A228116 A228117 A228118

Keyword

nonn

Author

Vladimir Pletser, Aug 10 2013

Status

approved