%I A036689
%S A036689 2,6,20,42,110,156,272,342,506,812,930,1332,1640,1806,2162,2756,3422,3660,
               4422,4970,5256,6162,6806,7832,9312,10100,10506,
%T A036689 11342,11772,12656,16002,17030,18632,19182,22052,22650,24492,26406,
%U A036689 27722,29756,31862,32580,36290,37056,38612,39402,44310
%N A036689 Product of a prime and previous number.
%C A036689 Records in A002618 - Artur Jasinski (grafix(AT)csl.pl), Jan 23 2008
%F A036689 a(n) = p(n)*[ p(n)-1 ] with p(n) the n-th prime.
%F A036689 a(n)=EulerPhi[Prime[n]^2] = A000010[A001248(n)]
%F A036689 a(n) = Prime[n] EulerPhi[Prime[n]] - Artur Jasinski (grafix(AT)csl.pl), 
               Jan 23 2008
%e A036689 a(2)=6 because p(2)=3 and p(2)-1=2.
%t A036689 Table[Prime[n] EulerPhi[Prime[n]], {n, 1, 100}] - Artur Jasinski (grafix(AT)csl.pl), 
               Jan 23 2008
%Y A036689 Cf. A001248, A002618, A053650, A053192, A053193, A053650.
%Y A036689 Cf. A002618.
%Y A036689 Sequence in context: A130315 A087150 A087134 this_sequence A139115 A121128 
               A056820
%Y A036689 Adjacent sequences: A036686 A036687 A036688 this_sequence A036690 A036691 
               A036692
%K A036689 nonn,easy
%O A036689 1,1
%A A036689 Felice Russo (felice.russo(AT)katamail.com)