Difference between 3^n and the product of primes less than or equal to n.

Terms

a(0) =0a(1) =2a(2) =7a(3) =21a(4) =75a(5) =213a(6) =699a(7) =1977a(8) =6351a(9) =19473a(10) =58839a(11) =174837a(12) =529131a(13) =1564293a(14) =4752939a(15) =14318877a(16) =43016691a(17) =128629653a(18) =386909979a(19) =1152561777a(20) =3477084711a(21) =10450653513a(22) =31371359919a(23) =93920085957a(24) =282206443611a(25) =847065516573