%I A001539
%S A001539 3,35,99,195,323,483,675,899,1155,1443,1763,2115,2499,2915,
%T A001539 3363,3843,4355,4899,5475,6083,6723,7395,8099,8835,9603,
%U A001539 10403,11235,12099,12995,13923,14883,15875,16899,17955
%N A001539 (4n+1)(4n+3).
%C A001539 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 (info(AT)polprimos.com), May 24 2008
%C A001539 (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 (qntmpkt(AT)yahoo.com), 
               Mar 01 2009]
%F A001539 Sum(k>=0, 1/a(k)) = Pi/8 - Benoit Cloitre (benoit7848c(AT)orange.fr), 
               Aug 20 2002
%F A001539 G.f.: (3+26*x+3*x^2)/(1-x)^3 [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), 
               Mar 07 2009]
%Y A001539 a(n) = A016826(n) - 1 = [A001533(n)+5]/4 = [A001538(n)+16]/9. Bisection 
               of A000466.
%Y A001539 Cf. A000290, A016286.
%Y A001539 Cf. A157142, A133766, A154633. [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), 
               Mar 07 2009]
%Y A001539 Sequence in context: A054783 A102104 A054287 this_sequence A113854 A076376 
               A133710
%Y A001539 Adjacent sequences: A001536 A001537 A001538 this_sequence A001540 A001541 
               A001542
%K A001539 nonn,easy
%O A001539 0,1
%A A001539 N. J. A. Sloane (njas(AT)research.att.com).