|
| |
|
|
A109840
|
|
Largest prime factor of the reverse concatenation of the first n consecutive odd numbers.
|
|
1
|
|
|
|
31, 59, 443, 13933, 2609, 83089, 18937669, 57697, 71615663503, 161768817795401, 4356390089, 4668342004597, 109230695824219, 2770122504473483, 217596035578054625221, 1721572826917, 659160492491
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
Table of n, a(n) for n=1..17.
|
|
|
EXAMPLE
|
n = 6: a(6) = 83089 because 131197531 = 1579 * 83089.
|
|
|
MATHEMATICA
|
s=1; ss={}; Do[news=FromDigits[Flatten[{IntegerDigits[n], IntegerDigits[s]}]]; fi=FactorInteger[news][[ -1, 1]]; s=news; AppendTo[ss, fi], {n, 3, 60, 2}]; A109840=ss
|
|
|
CROSSREFS
|
Cf. A109837 = smallest prime factor of the reverse concatenation of the first n consecutive odd numbers.
Sequence in context: A327447 A139954 A153636 * A108293 A316349 A063339
Adjacent sequences: A109837 A109838 A109839 * A109841 A109842 A109843
|
|
|
KEYWORD
|
base,nonn
|
|
|
AUTHOR
|
Zak Seidov, Jul 05 2005
|
|
|
STATUS
|
approved
|
| |
|
|
