A036333 Composite numbers n such that juxtaposition of prime factors of n has length 9.

512, 768, 1152, 1280, 1408, 1664, 1728, 1792, 1920, 2112, 2176, 2432, 2496, 2592, 2688, 2880, 2944, 3168, 3200, 3264, 3520, 3648, 3712, 3744, 3872, 3888, 3968, 4032, 4160, 4320, 4416, 4480, 4576, 4736, 4752, 4800, 4896, 4928, 5248, 5280, 5408, 5440

Offset: 1

Author

Patrick De Geest, Dec 15 1998

Keywords

• nonn
• base
• fini
• easy

Comments

The last term is a(84018465) = 997210243 = 9973 * 99991. - Giovanni Resta, Mar 21 2013

Prime factors counted with multiplicity. - Harvey P. Dale, Jul 26 2017

Links

• Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A036326-A036334.

Programs

Maple

isA036333 := proc(n) local d: d:=ifactors(n)[2]: return `if`(not isprime(n) and add(length(d[j][1])*d[j][2], j=1..nops(d))=9, n, NULL): end: seq(isA036333(n),n=2..5440); # Nathaniel Johnston, Jun 22 2011

Mathematica

jpf9Q[n_]:=CompositeQ[n]&&Total[IntegerLength[#[[1]]]#[[2]]&/@ FactorInteger[ n]]==9; Select[ Range[6000],jpf9Q] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 26 2017 *)