A087195 - OEIS

%I #3 Mar 30 2012 18:50:38

%S 7,13,25,31,37,49,57,97,109,133,151,183,193,307,325,381,385,393,553,

%T 751,769,871,973,993,1407,1453,1537,1723,1893,2257,2367,2745,2863,

%U 2917,3073,3541,3751,3783,4557,5113,5203,5403,6145,6321,6973,7221

%N Numbers of the form 1+(1+p)*p^e, p prime and e>0.

%C a(n) = 1+(1+A025473(k))*A000961(k) for some k>1, this k is unique except for n=2: a(2) = 13 = 1+(1+2)*2^2 = 1+(1+3)*3^1.

%e p=2, e=7: 1+(1+A000040(1))*A000040(1)^7 = 1+(1+2)*2^7 = 1+3*128 = 385 = a(17);

%e p=7, e=2: 1+(1+A000040(4))*A000040(4)^2 = 1+(1+7)*7^2 = 1+8*49 = 393 = a(18).

%Y Cf. A087196, A008864.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Aug 24 2003