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A190801 Least semiprime whose prime factors differ by n!. 0

%I #7 Mar 30 2012 18:35:55

%S 6,15,55,145,889,5089,55561,927889,6169249,39916921,678585889,

%T 13891047241,417210398089,1656387533161,56229997825849,

%U 481224167424529,11026310270976961,236887827111937369,10826413936386055921

%N Least semiprime whose prime factors differ by n!.

%C Appears to be the same as A037152(n) * A037153(n).

%e a(5) = 889 because 889 = 7 * 127 , and 127 - 7 = 120 = 5!

%t f[n_] := Block[{p=2}, While[! PrimeQ[p+n!], p=NextPrime[p]]; p*(p+n!)]; Table[f[n], {n, 60}]

%K nonn

%O 1,1

%A _Michel Lagneau_, May 20 2011

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Last modified April 25 03:15 EDT 2024. Contains 371964 sequences. (Running on oeis4.)