

A060820


(2*n1)^2 + (2*n)^2.


3



5, 25, 61, 113, 181, 265, 365, 481, 613, 761, 925, 1105, 1301, 1513, 1741, 1985, 2245, 2521, 2813, 3121, 3445, 3785, 4141, 4513, 4901, 5305, 5725, 6161, 6613, 7081, 7565, 8065, 8581, 9113, 9661, 10225, 10805, 11401, 12013, 12641, 13285, 13945, 14621, 15313
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


REFERENCES

Marilyn vos Savant and Leonore Fleischer, Brain Building in Just 12 Weeks, Bantam Books, New York, NY, 1991, pp. 104105, 119.


LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (3,3,1).


FORMULA

a(n) = 3*a(n1)3*a(n2)+a(n3). G.f.: x*(5+10*x+x^2)/(1x)^3.  Colin Barker, Apr 22 2012


EXAMPLE

a(1)=5 because 1^2+2^2=5. a(2)=25 because 3^2+4^2=25.


MATHEMATICA

Table[(2*n  1)^2 + (2*n)^2, {n, 300}] (* Vladimir Joseph Stephan Orlovsky, Feb 16 2012 *)
LinearRecurrence[{3, 3, 1}, {5, 25, 61}, 60] (* Harvey P. Dale, Oct 13 2020 *)


PROG

(PARI) for (n=1, 1000, write("b060820.txt", n, " ", (2*n  1)^2 + (2*n)^2); ) \\ Harry J. Smith, Jul 12 2009


CROSSREFS

Sequence in context: A228169 A152734 A080856 * A182211 A146404 A323187
Adjacent sequences: A060817 A060818 A060819 * A060821 A060822 A060823


KEYWORD

easy,nonn


AUTHOR

Jason Earls, May 05 2001


STATUS

approved



