A241852 - OEIS

A241852

Number m that give records for the difference between the maximum and minimum x's such that sigma(x)=m.

1, 12, 18, 24, 32, 42, 60, 72, 90, 140, 168, 224, 234, 252, 312, 360, 468, 480, 576, 588, 600, 684, 702, 720, 728, 744, 840, 864, 992, 1092, 1232, 1240, 1260, 1344, 1440, 1488, 1512, 1560, 1860, 1872, 2016, 2240, 2340, 2352, 2418, 2688, 2730, 2880, 3360, 3528

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..1000

EXAMPLE

Only sigma(1)=1, hence the first difference is 0.

The next m with several x's is 12 with sigma(6)=sigma(11)=12, difference 5 is > 0.

PROG

(PARI) sigv(n) = select(i->sigma(i) == n, vector(n, i, i));

ds(n) = {v = sigv(n); if (#v == 0, 0, vecmax(v) - vecmin(v)); }

lista(nn) = {dmax = -1; for (n=1, nn, if ((dv = ds(n)) > dmax, print1(n, ", "); dmax = dv; ); ); }