OFFSET
1,1
PROG
(PARI)
a360097(n)=my(k=1); while(isprime(2*n*k-1)||isprime(2*n*k+1), k++); k
a(n)=for(i=1, +oo, my(k=a360097(i)); if(k==n, return(i)))
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jean-Marc Rebert, Feb 01 2023
STATUS
approved