

A358602


Define u such that u(1) = k and u(n) = u(n1) + (1)^n*(n!) for n > 1. Terms are numbers k for which the number of consecutive values of u(i), starting at u(1) = k, that are primes reaches a new record high.


0




OFFSET

1,1


LINKS

Table of n, a(n) for n=1..8.


EXAMPLE

If k = 2, u(1) = 2 is prime, and no lesser number has this property, thus 2 is a term.
If k = 11, u(1) = 11, u(2) = 11 + 2! = 13, u(3) = 13  3! = 7 and u(4) = 7 + 4! = 31 are primes, and no lesser number has this property, thus 11 is a term.


PROG

(PARI)
card(k)=my(s=k, c=2, p=1); while(isprime(s), p*=c; s+=if(c%2, p, p); c++); c=2
rec(kk=10^9)=my(r=0); forprime(k=1, kk, x=card(k); if(x>r, if(r>0, print1(", ")); print1(k); r=x))


CROSSREFS

Sequence in context: A292710 A300898 A079853 * A050721 A058114 A042337
Adjacent sequences: A358599 A358600 A358601 * A358603 A358604 A358605


KEYWORD

nonn,more


AUTHOR

JeanMarc Rebert, Nov 23 2022


STATUS

approved



