cp's OEIS Frontend

A308533 Numbers such that the sum of anti-divisors divides the concatenation (in ascending order) of anti-divisors.

%I A308533 #16 Dec 14 2021 12:06:40
%S A308533 3,4,6,15,27,30,54,69,90,96,99,120,126,481,564,1050,1656,3480,7680,
%T A308533 9612,11520,393216,612846,2220864,5506086,5579652,8177664,18087936,
%U A308533 23711514,111544794,440477976,555176025
%N A308533 Numbers such that the sum of anti-divisors divides the concatenation (in ascending order) of anti-divisors.
%C A308533 Numbers k such that A066417(k) divides A130846(k).
%C A308533 Similar to A308486 where divisors are considered.
%e A308533 Anti-divisors of 1656 are 7, 11, 16, 43, 48, 77, 144, 301, 368, 473, 1104 and their sum is 2592. Then, 711164348771443013684731104 / 2592 = 274368961717377705896887.
%p A308533 P:=proc(q) local a,b,k,n; for n from 3 to q do a:=0: b:=0:
%p A308533 for k from 2 to n-1 do if abs((n mod k)-k/2)<1 then
%p A308533 a:=a*10^length(k)+k: b:=b+k: fi; od; if frac(a/b)=0 then print(n);
%p A308533 fi; od; end: P(10^6);
%o A308533 (Python)
%o A308533 from itertools import islice, count
%o A308533 from sympy.ntheory.factor_ import antidivisors
%o A308533 def A308533gen(): # generator of terms
%o A308533     for n in count(3):
%o A308533         a = antidivisors(n)
%o A308533         if int(''.join(str(s) for s in a)) % sum(a) == 0:
%o A308533             yield n
%o A308533 A308533_list = list(islice(A308533gen(),22)) # _Chai Wah Wu_, Dec 08 2021
%Y A308533 Cf. A066272, A066417, A130846, A308486.
%K A308533 base,nonn,more
%O A308533 1,1
%A A308533 _Paolo P. Lava_, Jun 06 2019
%E A308533 a(22)-a(30) from _Chai Wah Wu_, Dec 08 2021
%E A308533 a(31)-a(32) from _Chai Wah Wu_, Dec 14 2021