A360129 Numbers k such that A360119(k) > 1, but which have no divisors d > 1 such that d+1 is also a divisor.

572, 1144, 1292, 1768, 2288, 2584, 2590, 3496, 3596, 4030, 4576, 4930, 6292, 6992, 7052, 7192, 7436, 8050, 8170, 8246, 9044, 9152, 9212, 9430, 9724, 9758, 10868, 11408, 12136, 12584, 12950, 13984, 14104, 14212, 14384, 14396, 14872, 15370, 16168, 16492, 16588, 16796, 17066, 17168, 17732, 18130, 18304

Offset: 1

Author

Antti Karttunen, Feb 20 2023

Keywords

• nonn

Crossrefs

Subsequence of A088725.

Cf. A088722, A360119, A360128.

Programs

PARI

A360119(n) = { my(d=divisors(n), erot=vecsort(vector(#d-1, k, d[k+1] - d[k])), s=#d); for(i=1,#erot,if(n%erot[i], s--, if(1==i || erot[i]!=erot[i-1], s--))); (s); };
A360128(n) = !sumdiv(n,d,(d>1)&&!(n%(d+1)));
isA360129(n) = (A360128(n)&&(A360119(n)>1));

Formula

{k | A088722(k) = 0 and A360119(k) > 1}.