A328175 a(n) is the largest integer k such that sigma(k)/(d(k)*sopf(k)) = n where d=A000005, sigma=A000203 and sopf=A008472.

42, 470, 923, 2159, 12924, 3735, 4316, 8786, 23939, 24412, 76502, 26768, 28612, 47849, 145620, 36002, 118204, 189143, 116999, 105657, 109559, 252474, 142687, 236860, 504899, 265682, 388798, 1558808, 154559, 345687, 709564, 544829, 383086, 652049, 361905, 1193075

Offset

1,1

Links

Table of n, a(n) for n=1..36.

Prog

(PARI) sopf(f) = sum(j=1, #f~, f[j, 1]); \\ A008472
lista(nn) = {/* nn should be > 10^7 */ my(nmax = 43, v = vector(nmax, k, List())); for (n=2, nn, my(f=factor(n), q); if (denominator(q=sigma(f)/(numdiv(f)*sopf(f))) == 1, if (q <= nmax, listput(v[q], n)); ); ); for (i=1, nmax, if (#v[i] == 0, break); print1(vecmax(Vec(v[i])), ", "); ); }

Crossrefs

Cf. A000005, A000203, A008472, A134382, A328051, A328052, A328174.

Sequence in context: A090297 A008387 A088626 * A216109 A216111 A216113

Adjacent sequences: A328172 A328173 A328174 * A328176 A328177 A328178

Keyword

nonn

Author

Michel Marcus, Oct 06 2019

Status

approved