A087200 a(n) is the smallest m such that m > A005235(n) and A002110(n)+m is prime.

5, 7, 11, 17, 29, 29, 41, 37, 47, 89, 83, 101, 107, 67, 109, 73, 89, 167, 139, 229, 163, 193, 269, 157, 173, 523, 233, 157, 251, 193, 179, 383, 647, 311, 223, 317, 509, 457, 211, 503, 251, 479, 617, 1019, 347, 863, 827, 349, 389, 563, 601, 419, 367, 349, 449

Offset: 1

Author

Farideh Firoozbakht, Aug 26 2003

Keywords

• easy
• nonn

Comments

a(n) is the second m (first m is A005235(n)) such that m > 1 and A002110(n)+m is prime. I guess every term of this sequence (compare the conjecture about A005235) is prime. I checked this conjecture for n < 373.

References

• R. K. Guy, Unsolved Problems in Number Theory, Section A2.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A005235, A002110.

Programs

Mathematica

A005235[n_] := (For[m=2, !PrimeQ[Product[Prime[k], {k, n}]+m], m++ ]; m); a[n_] := (For[m=A005235[n]+1, !PrimeQ[Product[Prime[k], {k, n}]+m], m++ ]; m); Table[a[n], {n, 60}]