|
%I #17 Oct 12 2023 07:45:49
%S 1,201824,227799,313599,395199,544824,638000,654975,799799,862784,
%T 1056159,1204280,1269729,1447550,1890944,2276351,2460975,2481115,
%U 2781999,2821272,3348224,3382379,3403700,3832191,3864575,3956120,5142500,5961950,6116175,6401024,7050120
%N Numbers k such that k | A020696(k) and (k+1) | A020696(k+1).
%C Numbers k such that k and k+1 are both in A355331.
%C Are there 3 consecutive integers in A355331?
%C There are no such 3 consecutive integers below 10^10. - _Amiram Eldar_, Oct 12 2023
%H Amiram Eldar, <a href="/A355332/b355332.txt">Table of n, a(n) for n = 1..2000</a>
%e 1 is a term since A020696(1) = 2 is divisible by 1 and A020696(2) = 6 is divisible 2.
%t q[n_] := Divisible[Times @@ (Divisors[n] + 1), n]; Select[Range[10^6], q[#] && q[#+1] &]
%o (PARI) f(n) = my(d = divisors(n)); prod(i=1, #d, d[i]+1); \\ A020696
%o isok(k) = !(f(k) % k) && !(f(k+1) % (k+1)); \\ _Michel Marcus_, Jun 30 2022
%Y Cf. A020696, A355331.
%K nonn
%O 1,2
%A _Amiram Eldar_, Jun 29 2022
|
