cp's OEIS Frontend

A182081 Next semiprime after the partial sum of the first n semiprimes.

%I A182081 #10 Apr 10 2012 22:32:27
%S A182081 6,14,21,33,46,62,82,106,129,155,187,221,259,295,334,381,427,478,533,
%T A182081 591,649,713,778,849,921,995,1077,1165,1253,1337,1437,1522,1618,1711,
%U A182081 1814,1927,2041,2159,2279,2402,2533,2643,2773,2906,3039,3183,3326,3466,3611
%N A182081 Next semiprime after the partial sum of the first n semiprimes.
%C A182081 This is to A202301 next prime after the partial sum of the first n primes as A001358 semiprimes is to A000040 primes.
%H A182081 Alois P. Heinz, <a href="/A182081/b182081.txt">Table of n, a(n) for n = 1..1000</a>
%F A182081 a(n) = min { k > A062198(n) and k in A001358 }.
%e A182081 a(10) = 155 because 4 + 6 + 9 + 10 + 14 + 15 + 21 + 22 + 25 + 26 = 152, and the next semiprime after 152 is 155.
%p A182081 h:= proc(m) local k;
%p A182081       for k from m+1 while isprime(k) or
%p A182081         add (i[2], i=ifactors(k)[2])<>2 do od; k
%p A182081     end:
%p A182081 b:= proc(n)
%p A182081       b(n):= h(b(n-1))
%p A182081     end: b(0):=0:
%p A182081 s:= proc(n)
%p A182081       s(n):= b(n) +s(n-1)
%p A182081     end: s(0):=0:
%p A182081 a:= n-> h(s(n)):
%p A182081 seq (a(n), n=1..60); # _Alois P. Heinz_, Apr 10 2012
%Y A182081 Cf. A001358, A062198, A202301.
%K A182081 nonn,easy
%O A182081 1,1
%A A182081 _Jonathan Vos Post_, Apr 10 2012
%E A182081 More terms from _Alois P. Heinz_, Apr 10 2012