cp's OEIS Frontend

A192283 Sum of prime anti-divisors of n = sum of prime anti-divisors of n+1 with n > 1.

%I A192283 #10 Mar 30 2012 18:53:49
%S A192283 237,4019,7401,14178,14339,18435,19146,21405,54562,56348,60125,82967,
%T A192283 98447,99347,109157,113391,125333,132096,132386,145063,173399,195213,
%U A192283 260288,278271,343848,384169,396813,434375,460758,474105,477707,528845,550400,587211
%N A192283 Sum of prime anti-divisors of n = sum of prime anti-divisors of n+1 with n > 1.
%C A192283 Like A006145 but using anti-divisors.
%H A192283 Donovan Johnson, <a href="/A192283/b192283.txt">Table of n, a(n) for n = 1..1000</a>
%e A192283 Anti-divisors of 7401 are 2, 6, 19, 41, 113, 131, 361, 779, 4934. The primes are 2, 19, 41, 113 and 131 whose sum is 306.
%e A192283 Anti-divisors of 7402 are 3, 4, 5, 7, 9, 15, 21, 35, 45, 47, 63, 105, 113, 131, 141, 235, 315, 329, 423, 705, 987, 1645, 2115, 2961, 4935. The primes are 3, 5, 7, 47, 113 and 131 whose sum is 306.
%p A192283 with(numtheory);
%p A192283 P:=proc(n)
%p A192283 local a,b,i,k;
%p A192283 b:=2;
%p A192283 for i from 4 to n do
%p A192283   a:=0;
%p A192283   for k from 2 to i-1 do
%p A192283     if abs((i mod k)- k/2) < 1 then if isprime(k) then a:=a+k; fi; fi;
%p A192283   od;
%p A192283   if a=b then print(i-1); fi;
%p A192283   b:=a;
%p A192283 od;
%p A192283 end:
%p A192283 P(200000);
%Y A192283 Cf. A002961, A006145, A066272, A192282
%K A192283 nonn
%O A192283 1,1
%A A192283 _Paolo P. Lava_, Jul 27 2011