A385858 Numbers m in A385402 which are not prime.

1, 35, 77, 95, 119, 125, 143, 187, 209, 221, 247, 259, 299, 319, 323, 377, 391, 403, 427, 437, 473, 493, 527, 551, 589, 629, 667, 697, 713, 731, 779, 799, 817, 851, 893, 899, 943, 989, 1007, 1073, 1139, 1147, 1189, 1199, 1219, 1247, 1271, 1313, 1333, 1343, 1357, 1363, 1387, 1397

Offset: 1

Author

Robert G. Wilson v, Jul 10 2025

Keywords

• nonn

Comments

Since all the primes are in A385402, this sequence is more concise.

Crossrefs

Cf. A018804, A384628, A385398.

Proper subset of A385402.

Programs

Mathematica

fQ[m_] := Sum[ GCD[m, Floor[m/k]], {k, m}] == Sum[ GCD[m, Ceiling[m/k]], {k, m}]; j = 1; lst = {}; While[j < 1400, If[ !PrimeQ@ j && fQ@ j, AppendTo[lst, j]]; j++]; lst

PARI

isok(m) = if (!isprime(m), sum(k=1, m, gcd(m, floor(m/k))) == sum(k=1, m, gcd(m, ceil(m/k)))); \\ Michel Marcus, Jul 10 2025