A066410 Maximal sum of divisors of any n-digit number.

15, 252, 3048, 34560, 403200, 4390848, 45732192, 487710720, 5079674880, 52124083200, 542890252800, 5618427494400, 58517854617600, 591272607744000, 6026281863275520, 60762014342184960, 623846047297536000, 6394202229664972800, 64417520701204070400, 652677739551129600000

Offset

1,1

Links

Table of n, a(n) for n=1..20.

Example

a(1) = 15 since sigma(8) is 15 and that is the record for 1-digit numbers.

Mathematica

a[n_] := Module[{mx=1}, For[k=10^(n-1), k<=10^n-1, k++, If[(t=DivisorSigma[1, k]) > mx, mx=t; kx=k]]; mx]; Array[a, 6] (* Stefano Spezia, Nov 07 2024 *)

Prog

(PARI) maxsigdig(m, n)= { local(d, a, k, b); for(d=m, n, a=0; for(k=10^d, 10^(d+1)-1, b=sigma(k); if(b>a, a=b)); print1(a, ", "))}
maxsigdig(0, 7)

Crossrefs

Cf. A000203, A066424.

Sequence in context: A331493 A093147 A218192 * A370317 A116508 A055659

Adjacent sequences: A066407 A066408 A066409 * A066411 A066412 A066413

Keyword

base,nonn,changed

Author

Jason Earls, Dec 25 2001

Extensions

More terms from Vladeta Jovovic, Dec 26 2001

Status

approved