This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A138961 a(n) = largest prime divisor of A138957(n). 6
 1, 3, 41, 617, 823, 643, 9721, 14593, 3803, 14405693, 10939223, 4156374407, 2663693, 5603770631, 1221751714624799, 287108811653770498027, 74103167823547, 11843077531813991, 726216405947772436185983423, 769725127, 18274551225153265813469 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For smallest prime divisors see A138960. LINKS Robert Price, Table of n, a(n) for n = 1..60 MATHEMATICA a = {}; b = {}; Do[w = RealDigits[n]; w = First[w]; Do[AppendTo[a, w[[Length[w] - k + 1]]], {k, 1, Length[w]}]; p = FromDigits[a]; AppendTo[b, First[Last[FactorInteger[p]]]], {n, 1, 18}]; b A137957[n_] := FromDigits[Flatten[Reverse /@ IntegerDigits[Range[n]]]]; Table[First[Last[FactorInteger[A137957[n]]]], {n, 39}] (* Robert Price, May 10 2019 *) CROSSREFS Cf. A104759, A000422, A116504, A007908, A116505, A104759, A138789, A138790, A138958, A138960. Sequence in context: A189356 A155672 A073844 * A075022 A300281 A012175 Adjacent sequences:  A138958 A138959 A138960 * A138962 A138963 A138964 KEYWORD nonn,base AUTHOR Artur Jasinski, Apr 04 2008 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.

Last modified July 18 15:26 EDT 2019. Contains 325143 sequences. (Running on oeis4.)