



3, 35, 99, 195, 323, 483, 675, 899, 1155, 1443, 1763, 2115, 2499, 2915, 3363, 3843, 4355, 4899, 5475, 6083, 6723, 7395, 8099, 8835, 9603, 10403, 11235, 12099, 12995, 13923, 14883, 15875, 16899, 17955, 19043, 20163, 21315, 22499, 23715, 24963, 26243, 27555
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,1


COMMENTS

Sequence arises from reading the line from 3, in the direction 3, 35,... in the square spiral whose vertices are the squares A000290.  Omar E. Pol, May 24 2008
(log(sq(2)+1))/sqrt(2) = .62322524...= 2/3  2/35 + 2/99  2/195 + 2/323,...; = (1  1/3) + (1/7  1/5) + (1/9  1/11) + (1/15  1/13) + (1/17  1/19) + (1/23  1/21) + ... [From Gary W. Adamson, Mar 01 2009]


LINKS

T. D. Noe, Table of n, a(n) for n = 0..1000
Index entries for sequences related to linear recurrences with constant coefficients, signature (3,3,1).


FORMULA

Sum(k>=0, 1/a(k)) = Pi/8  Benoit Cloitre, Aug 20 2002
G.f.: (3+26*x+3*x^2)/(1x)^3 [From Jaume Oliver Lafont, Mar 07 2009]
a(n)=32*n+a(n1), with a(0)=3 [From Vincenzo Librandi,


PROG

(Maxima) A001539(n):=(4*n+1)*(4*n+3)$
makelist(A001539(n), n, 0, 30); /* Martin Ettl, Nov 12 2012 */


CROSSREFS

a(n) = A016826(n)  1 = [A001533(n)+5]/4 = [A001538(n)+16]/9.
Bisection of A000466.
Cf. A000290, A016286.
Cf. A157142, A133766, A154633.
Sequence in context: A054287 A176761 A246824 * A113854 A231645 A076376
Adjacent sequences: A001536 A001537 A001538 * A001540 A001541 A001542


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane.


STATUS

approved



