A236355 Terms of A050973 that give maximum record values for A050973(k)/A050972(k).

28, 224, 234, 496, 6200, 8128, 174592, 544635, 2886100, 33550336

Offset

1,1

Comments

The corresponding terms in A050972 are: 6, 40, 12, 6, 30, 6, 40, 6, ...

Note the subsequence 28, 496, 8128, 33550336: friends of 6 (cf A000396).

Links

Table of n, a(n) for n=1..10.

Eric Weisstein's World of Mathematics, Friendly Pair.

Example

28/6 < 224/40 < 234/12 < 496/6 < 6200/30 < 8128/6 < 174592/40 < ....

Prog

(PARI) isrmax(i, rmax) = {si = sigma(i); if (gcd(si, i) == 1, return (0)); s = si/i; for (j=1, i\rmax, if ((sigma(j)/j) == s, if ((newr = i/j) > rmax, return (newr)); ); ); return (0); }
lista(nn) = {rmax = 1; for (i = 1, nn, if ((newr = isrmax(i, rmax)), rmax = newr; print1(i, ", "); ); ); }

Crossrefs

Cf. A050972, A050973, A236372.

Sequence in context: A249710 A269621 A269437 * A133071 A339137 A135180

Adjacent sequences: A236352 A236353 A236354 * A236356 A236357 A236358

Keyword

nonn,more

Author

Michel Marcus, Jan 23 2014

Status

approved