login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A047739 Economical palindromes. 0
343, 1331, 10201, 14641, 31213, 94249, 1030301, 1332331, 1367631, 1478741, 2060602, 2513152, 2551552, 2570752, 2939392, 2977792, 3090903, 3498943, 3637363, 3735373, 3850583, 5221225, 5265625, 5734375, 6948496, 11288211, 11333311, 12100121, 12499421, 13577531, 14655641, 22666622, 27700772, 29399392, 31244213, 33999933, 38988983, 58344385, 71111117, 100020001, 100585001, 101000101, 104060401, 104555401, 106878601 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..45.

EXAMPLE

343 = 7^3; 3 digits in 343, 2 digits in 7^3, so 343 is economical.

MATHEMATICA

d[n_]:=IntegerDigits[n]; palQ[n_]:=Reverse[(x=d[n])]==x; ecQ[n_]:=Length[Flatten[d[{First/@(x=FactorInteger[n]), DeleteCases[Last/@x, 1]}]]] < Length[d[n]]; t={}; Do[If[palQ[n] && ecQ[n], AppendTo[t, n]], {n, 3860000}]; t (* Jayanta Basu, May 16 2013 *)

CROSSREFS

Cf. A046759.

Sequence in context: A117689 A178374 A179147 * A052084 A075546 A167733

Adjacent sequences:  A047736 A047737 A047738 * A047740 A047741 A047742

KEYWORD

nonn,base

AUTHOR

Carlos Rivera

EXTENSIONS

a(11)-a(45) from Donovan Johnson, Nov 24 2010

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 17 15:19 EDT 2019. Contains 325106 sequences. (Running on oeis4.)