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%I #10 Dec 22 2021 18:18:35
%S 8,2,2,12,6,10,2,6,12,2,4,12,2,10,2,4,10,6,4,4,12,24,10,10,10,4,2,30,
%T 10,4,4,30,12,2,10,4,10,10,54,10,12,22,10,24,2,4,88,16,16,22,30,6,60,
%U 12,2,8,22,30,10,10,88,6,34,6,22,22,94,40,6,30,4,100,40,16,40,4,36,20,4,16,18
%N Difference between the first odd semiprime > 7^n and 7^n.
%C A098147 is the difference between the first odd semiprime > 10^n and 10^n.
%F a(n) = minimum integer k such that 7^n + k is an element of A046315. a(n) = minimum integer k such that A000420(n) + k is an element of A046315.
%e a(0) = 8 because 7^0 + 8 = 9 = 3^2 is an odd semiprime.
%e a(1) = 2 because 7^1 + 2 = 9 = 3^2 is an odd semiprime.
%e a(2) = 2 because 7^2 + 2 = 51 = 3*17 is an odd semiprime.
%e a(3) = 12 because 7^3 + 12 = 355 = 5 * 71.
%e a(4) = 6 because 7^4 + 6 = 2407 = 29 * 83 (brilliant).
%e a(5) = 10 because 7^5 + 10 = 16817 = 67 * 251.
%Y Cf. A000351, A001358, A098147.
%K easy,nonn
%O 0,1
%A _Jonathan Vos Post_, Feb 05 2006
%E Corrected and extended by _Don Reble_, Oct 16 2017
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