OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
a(n)=8*A000537(n) + 1.
a(n)=1+2*n^2+4*n^3+2*n^4. G.f.: -(x^4+4*x^3+38*x^2+4*x+1)/(x-1)^5. [Colin Barker, Jul 28 2012]
EXAMPLE
1801 is in the sequence because we may for instance write 1800 = 6^2 + 42^2; 1801 = 24^2 + 35^2; 1802 = 29^2 + 31^2.
MATHEMATICA
LinearRecurrence[{5, -10, 10, -5, 1}, {1, 9, 73, 289, 801}, 40] (* Harvey P. Dale, Oct 22 2019 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Lekraj Beedassy, Jul 23 2004
EXTENSIONS
Corrected and extended by Ray Chandler, Jul 29 2004
STATUS
approved