a(1)=1, a(2)=4, and thereafter a(n) = a(n-2) + k * a(n-1), with minimal k >= 1 such that a(n) is not prime.

A374055

a(1)=1, a(2)=4, and thereafter a(n) = a(n-2) + k * a(n-1), with minimal k >= 1 such that a(n) is not prime.

Terms

    a(0) =1a(1) =4a(2) =9a(3) =22a(4) =75a(5) =172a(6) =247a(7) =666a(8) =913a(9) =2492a(10) =3405a(11) =9302a(12) =12707a(13) =22009a(14) =34716a(15) =56725a(16) =91441a(17) =148166a(18) =239607a(19) =387773a(20) =627380a(21) =1015153a(22) =1642533a(23) =2657686a(24) =4300219a(25) =6957905a(26) =11258124a(27) =18216029a(28) =29474153a(29) =47690182

External references