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 A141233 Sequence of k such that starting with P(0)=7 then k(n)*P(n-1)*(k(n)*P(n-1)-1)-1 is the least prime = P(n). 7
 1, 4, 1, 19, 16, 56, 80, 383, 235 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE 1*7*7-1*7-1=41 prime so k(1)=1 P(1)=41; 1*41*(1*41-1)-1=1639 composite, 2*41*(2*41-1)-1=6641 composite, 3*41*(3*41-1)-1=15005 composite, 4*41*(4*41-1)-1=26731 prime so k(2)=4 P(2)=26731; 1*26731*(1*26731-1)-1=714519629 prime so k(3)=1 P(3)=714519629. PROG (PARI) P=7; for(i=1, 20, k=0; while(!ispseudoprime(t=k++*P*(k*P-1)-1), ); P=t; print1(k", ")) \\ Michel Marcus, Sep 16 2019 ; after A141240 CROSSREFS Cf. A141234, A141235, A141236, A141237, A141238, A141239, A141240. Sequence in context: A192722 A300141 A057968 * A055139 A249716 A333273 Adjacent sequences:  A141230 A141231 A141232 * A141234 A141235 A141236 KEYWORD nonn,more AUTHOR Pierre CAMI, Jun 16 2008 STATUS approved

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Last modified April 17 10:52 EDT 2021. Contains 343064 sequences. (Running on oeis4.)