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%I #7 Nov 11 2019 09:24:56
%S 1,2,3,2,4,0,5,3,4,0,3,1,7,0,2,2,6,0,3,3,2,0,5,1,3,0,3,3,3,0,9,3,3,0,
%T 4,3,3,0,3,4,6,0,6,2,1,0,7,1,5,0,6,2,3,0,3,3,3,0,6,1,6,0,5,4,5,0,2,4,
%U 5,0,6,2,7,0,3,1,8,0,5,2,6,0,5,0,6,0,2,5,6,0,5,4,1,0,5,1,4,0,4,0,6,0,3,4,3
%N Number of primes of the form 2^(n-m) 3^m - 1, 0 <= m <= n.
%H M. Underwood, <a href="http://groups.yahoo.com/group/primenumbers/message/21119">2^a*3^b one away from a prime</a>. Post to primenumbers group, Nov. 19, 2009.
%H Mark Underwood, Jens Kruse Andersen, <a href="/A167504/a167504.txt">2^a*3^b one away from a prime</a>, digest of 3 messages in primenumbers Yahoo group, Nov 19, 2009.
%o (PARI) A167504(n)=sum(b=0,n,ispseudoprime(3^b<<(n-b)-1))
%K nonn
%O 1,2
%A _M. F. Hasler_, Nov 19 2009