A195330 Numbers n such that A080670(n) < n.

32, 64, 81, 121, 125, 128, 169, 243, 256, 289, 320, 343, 361, 375, 384, 405, 448, 486, 512, 529, 567, 625, 640, 686, 729, 768, 841, 875, 896, 961, 1024, 1029, 1215, 1250, 1280, 1331, 1369, 1458, 1536, 1681, 1701, 1715, 1792, 1849, 1875, 2048, 2187, 2197, 2209, 2401, 2430, 2500, 2560, 2592, 2656, 2662, 2738, 2744, 2752, 2809, 2816, 2848, 2916, 2944, 3008, 3072, 3104, 3125, 3136, 3200, 3328, 3362, 3375, 3392, 3402, 3430, 3456, 3481, 3483, 3584, 3645, 3698, 3712

Offset: 1

Author

N. J. A. Sloane, Sep 15 2011

Keywords

• nonn
• base

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..10000 (first 220 terms from Robert Price)

Crossrefs

Cf. A080670, A195331, A194263.

Programs

Maple

b:= proc(n) option remember; `if`(n=1, 1, (l->
      parse(cat(seq(`if`(l[i, 2]=1, l[i, 1], [l[i, 1],
      l[i, 2]][]), i=1..nops(l)))))(sort(ifactors(n)[2])))
    end:
a:= proc(n) option remember; local k; for k from
      `if`(n=1, 0, a(n-1))+1 while b(k)>=k do od; k
    end:
seq(a(n), n=1..100);  # Alois P. Heinz, Mar 17 2020

Mathematica

A080670 = Cases[Import["https://oeis.org/A080670/b080670.txt", "Table"], {, }][[All, 2]];
Select[Range[3712], A080670[[#]] < # &] (* Robert Price, Mar 17 2020 *)

PARI

is(n,f=factor(n))=eval(concat(vector(#f~,i,if(f[i,2]==1, Str(f[i,1]), Str(f[i,1],f[i,2])))))Charles R Greathouse IV, Mar 18 2020