A087201 a(n) is the smallest m such that m > A055211(n) and A002110(n)-m is prime.

11, 13, 17, 19, 47, 37, 61, 67, 79, 107, 53, 149, 97, 89, 109, 223, 107, 179, 181, 101, 197, 101, 257, 139, 137, 197, 313, 257, 257, 223, 449, 373, 233, 463, 479, 409, 257, 409, 383, 317, 587, 607, 401, 463, 347, 313, 751, 313, 443, 349, 809, 661, 587, 367

Offset: 3

Author

Farideh Firoozbakht, Aug 27 2003

Keywords

• easy
• nonn

Comments

a(1) and a(2) are not defined. a(n) is the second m (first m is A055211(n)) such that m > 1 and A002110(n)-m is prime. I guess every term of this sequence (compare the conjecture about A055211) is prime. I checked this conjecture for n < 418.

Crossrefs

Cf. A055211, A002110, A087200.

Programs

Mathematica

A055211[n_] := (For[m=2, !PrimeQ[Product[Prime[k], {k, n}]-m], m++ ]; m); a[n_] := (For[m=A055211[n]+1, !PrimeQ[Product[Prime[k], {k, n}]-m], m++ ]; m); Table[a[n], {n, 3, 62}]

Formula

A055211[n_] := (For[m=2, !PrimeQ[Product[Prime[k], {k, n}]-m], m++ ]; m); a[n_] := (For[m=A055211[n]+1, !PrimeQ[Product[Prime[k], {k, n}]-m], m++ ]; m);