A377953 - OEIS

%I #12 Nov 16 2024 04:29:24

%S 310155,2566025,2853135,5746455,6515145,7329608,8459360,11291091,

%T 15446079,16181535,26782224,26942475,32364464,34318844,36951200,

%U 38579442,38596239,38763900,40564524,41273154,47308976,47648600,49309715,50163735,51177224,52573520,58524465,63668079

%N Numbers k such that k | A084190(k) and (k+1) | A084190(k+1).

%C Numbers k such that k and k+1 are both terms in A377952.

%H Amiram Eldar, <a href="/A377953/b377953.txt">Table of n, a(n) for n = 1..1500</a>

%t q[n_] := q[n] = n == 1 || Divisible[LCM @@ (Rest @ Divisors[n] - 1), n] ; Select[Range[3*10^6], q[#] && q[# + 1] &]

%o (PARI) is1(k) = !(lcm(apply(x -> if(x > 1, x-1, x), divisors(k))) % k);

%o lista(kmax) = {my(q1 = is1(1), q2); for(k = 2, kmax, q2 = is1(k); if(q1 && q2, print1(k-1, ", ")); q1 = q2);}

%Y Cf. A084190.

%Y Subsequence of A377952.

%Y Similar sequences: A355332, A377949, A377951.

%K nonn,changed

%O 1,1

%A _Amiram Eldar_, Nov 12 2024