OFFSET
0,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..10000
R. Sitaramachandrarao and P. V. Krishnaiah, On the sums Sigma_{n<=x} A(f(n)) and Sigma_{p<=x} A(f(p)), Journal of Number Theory, Vol. 23, No. 2 (1986), pp. 149-168.
FORMULA
a(n) ~ (40*G/Pi^2) * n^3, where G is Catalan's constant (A006752).
EXAMPLE
MATHEMATICA
Accumulate @ Table[SquaresR[4, k^2 + 1], {k, 0, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Mar 09 2020
STATUS
approved