

A100474


a(1) = 1; a(n) is the smallest integer such that a(n) + a(n1) has the first n distinct prime factors not used before in this construction.


0



1, 5, 380, 96197, 58546472, 42588477041, 42945524659398, 62170660055541623, 133274332258941430724, 322874181064180119947025, 950049250593734799731643802, 4193776877793643794299905615515
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OFFSET

1,2


COMMENTS

a(11) is the first semiprime in the sequence. What is the next? After a(2) = 5, is there another prime?


LINKS



FORMULA



EXAMPLE

a(2) = 5 because 5 + a(1) = 2 * 3.
a(3) = 380 because 380 + a(2) = 5 * 7 * 11.
a(4) = 96197 because 96197 + a(3) = 13 * 17 * 19 * 23 (note that 96197 is coincidentally the 3brilliant 19 * 61 * 83).


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



