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 A109907 Beginning with 7, a(n+1) = greatest prime of the form k*{a(n)-k}-1. If no prime is obtained the sequence ends at that point. 2
 7, 11, 29, 197, 9689, 23469167, 137700449916401, 4740353476794815041972197893, 5617737771240172767652929826457529708578746492288409399, 7889744416604625924469156192031986939513870147397674409917489724005347434748024264638497225986334149357868007 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Conjecture: The sequence is infinite. LINKS PROG (PARI) { b(n) = forstep(k=n\2, 1, -1, if(isprime(k*(n-k)-1), return(k*(n-k)-1))); return(0) } s=7; while(1, print1(s, " "); s=b(s)) (Alekseyev) CROSSREFS Cf. A109904, A109905, A026728, A109908, A109909. Sequence in context: A045461 A153867 A153325 * A121534 A083363 A027707 Adjacent sequences:  A109904 A109905 A109906 * A109908 A109909 A109910 KEYWORD nonn AUTHOR Amarnath Murthy, Jul 15 2005 EXTENSIONS More terms from Max Alekseyev, Oct 04 2005 STATUS approved

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Last modified February 17 10:59 EST 2019. Contains 320219 sequences. (Running on oeis4.)