login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A095409 Numbers n such that total number of decimal digits of all distinct prime factors of n is smaller than number of digits of n. 2
1, 16, 25, 27, 32, 49, 64, 81, 100, 108, 112, 121, 125, 128, 135, 144, 147, 160, 162, 169, 175, 189, 192, 196, 200, 216, 224, 225, 243, 245, 250, 256, 288, 289, 320, 324, 343, 361, 375, 384, 392, 400, 405, 432, 441, 448, 486, 500, 512, 529, 567, 576, 625, 640 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
Solutions to A095407[x] < A055642[x].
EXAMPLE
n=100: prime set={2,5}, 3 digits and 2 digits of prime factors, so 100 is here;
n=147: prime set={3,7}, 3 digits and 2 digits of [ -factors, so 147 is here.
MATHEMATICA
ffi[x_] :=Flatten[FactorInteger[x]] lf[x_] :=Length[FactorInteger[x]] ba[x_] :=Table[Part[ffi[x], 2*j-1], {j, 1, lf[x]}] tdp[x_] :=Flatten[Table[IntegerDigits[Part[ba[x], j]], {j, 1, lf[x]}], 1] pl[x_] :=Length[tdp[x]] nl[x_] :=Length[IntegerDigits[x]] t1=Table[nl[w], {w, 1, 1000}]; t2=Table[pl[w], {w, 1, 1000}]; t2-t1 Flatten[Position[t2-t1, -1]]
CROSSREFS
Sequence in context: A334392 A227651 A348320 * A339624 A111026 A124186
KEYWORD
base,nonn
AUTHOR
Labos Elemer, Jun 21 2004
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 19 08:45 EDT 2024. Contains 371782 sequences. (Running on oeis4.)