A074836 - OEIS

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

A074836

a(1) = 1, a(n) = the largest prime divisor of concatenation of sequence (n,n-1,..,2,1,2,..,n-1,n) A007942.

53, 353, 2160617, 479, 146053847, 18533465459, 18588601, 444444443, 10987654321234567891, 41824630287288128897, 24899126702236725259, 131211109876543212345678910111213, 59722151033999393, 1081735780698166140181, 40378532802777469135803086419727527803285379

(list; graph; refs; listen; history; text; internal format)

OFFSET

2,1

LINKS

Table of n, a(n) for n=2..16.

M. Fleuren, Smarandache Mirror Sequence.

EXAMPLE

a(4) is 2160617 because 4321234 = 2.'2160617'.

MATHEMATICA

Table[FactorInteger[FromDigits[Join[Flatten[IntegerDigits/@ Range[ n, 1, -1]], Flatten[IntegerDigits/@Range[2, n]]]]][[-1, 1]], {n, 2, 15}] (* Harvey P. Dale, Sep 05 2015 *)

CROSSREFS

Cf. A007942.

Sequence in context: A174441 A094249 A244771 * A142851 A185239 A053736

Adjacent sequences: A074833 A074834 A074835 * A074837 A074838 A074839

KEYWORD

nonn,base

AUTHOR

Jason Earls, Sep 09 2002

EXTENSIONS

Edited by Charles R Greathouse IV, Apr 28 2010

More terms from Harvey P. Dale, Sep 05 2015

STATUS

approved