A196128 - OEIS

A196128

Largest prime p[i] such that p[i]+p[i+1]+...+p[i+n-1] <= primorial(n) = A002110(n).

2, 2, 5, 43, 449, 4987, 72901, 1212427, 24787981, 646969237, 18232771699, 618394844407, 23403866424979, 934482952261687, 40992652172565871, 2036822404824377491, 113103550009071331379, 6516021186633720609839, 413595871109487739782749, 27897041506334948048370371

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OFFSET

1,1

COMMENTS

It is not known whether there is n (necessarily even) such that p[i]+p[i+1]+...+p[i+n-1] = primorial(n) for some p[i].

LINKS

Table of n, a(n) for n=1..20.

J. M. Bergot, C. Rivera (Ed.), Problem 56. p1*p2*…*pk = q1+q2+…+qk, on primepuzzle.net.

PROG

(PARI) A196128(k)={my(P=A002110(k), S=precprime(P\k), p=S, q=S); for(n=1, k, S+=if(S*k>P*n, p=precprime(p-1), q=nextprime(q+1))); p}

CROSSREFS

Cf. A196129, A196130.