1,2

a(n) = A106349(n) - A106350(n).

a(1) = prime(semiprime(1)) - semiprime(prime(1)) = prime(4) - semiprime(2) = 7 - 6 = 1.

a(2) = prime(semiprime(2)) - semiprime(prime(2)) = prime(6) - semiprime(3) = 13 - 9 = 4.

a(3) = prime(semiprime(3)) - semiprime(prime(3)) = prime(9) - semiprime(5) = 23 - 14 = 9.

a(4) = prime(semiprime(4)) - semiprime(prime(4)) = prime(10) - semiprime(7) = 29 - 21 = 8.

Cf. A000040, A001358, A106349, A106350.

Sequence in context: A081382 A019784 A011381 this_sequence A093491 A140808 A163642

Adjacent sequences: A122821 A122822 A122823 this_sequence A122825 A122826 A122827

easy,nonn

Jonathan Vos Post (jvospost3(AT)gmail.com), Oct 23 2006