Expansion of Product_{k>=1} ((1+x^k)/(1-x^k))^(2^k).

Terms

a(0) =1a(1) =4a(2) =16a(3) =60a(4) =208a(5) =692a(6) =2224a(7) =6940a(8) =21152a(9) =63188a(10) =185488a(11) =536268a(12) =1529648a(13) =4310804a(14) =12017264a(15) =33171916a(16) =90745472a(17) =246201412a(18) =662897232a(19) =1772295020a(20) =4707336848a(21) =12426673188a(22) =32617079280a(23) =85152717404a(24) =221183486496a(25) =571784014244