Engel expansion of Pi^2/6, or zeta(2) = 1.64493.

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =9a(5) =22a(6) =35a(7) =79a(8) =2992a(9) =3597a(10) =17523a(11) =28632a(12) =41470a(13) =53093a(14) =57406a(15) =14504930a(16) =42622213a(17) =188335162a(18) =322429556a(19) =1023003875a(20) =1328535963a(21) =3138645732a(22) =11618168524a(23) =137721814936a(24) =156929353744a(25) =166732460513a(26) =813398686532