A241853 Records of the difference between the maximum and minimum x's such that sigma(x)=m.

0, 5, 7, 9, 10, 21, 35, 41, 49, 63, 107, 139, 143, 155, 185, 239, 269, 311, 317, 327, 383, 389, 395, 455, 475, 503, 527, 533, 655, 695, 715, 727, 739, 851, 887, 959, 1031, 1055, 1169, 1241, 1267, 1483, 1547, 1571, 1697, 1763, 1793, 2039, 2219, 2279, 2347

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(dv, ", "); dmax = dv; ); ); }

Crossrefs

Cf. A241852 (corresponding m's).

Sequence in context: A158251 A212191 A336122 * A165513 A002342 A080353

Adjacent sequences: A241850 A241851 A241852 * A241854 A241855 A241856

Keyword

nonn

Author

Michel Marcus, Apr 30 2014

Status

approved