Greatest common divisor of 2^n-1 and 5^n-1.

Terms

a(0) =1a(1) =3a(2) =1a(3) =3a(4) =1a(5) =63a(6) =1a(7) =3a(8) =1a(9) =33a(10) =1a(11) =819a(12) =1a(13) =3a(14) =31a(15) =51a(16) =1a(17) =3591a(18) =1a(19) =1353a(20) =1a(21) =69a(22) =1a(23) =819a(24) =1a(25) =3a(26) =1a(27) =87a(28) =1a(29) =21483