|
| |
|
|
A076527
|
|
Numbers n such that sopf(n) = sopf(n-1) - sopf(n-2), where sopf(x) = sum of the distinct prime factors of x.
|
|
7
|
|
|
|
8, 66, 2883, 3264, 3552, 13872, 21386, 26896, 29698, 29768, 31980, 36567, 40517, 65305, 72012, 82719, 101639, 110848, 160230, 211646, 237136, 237568, 238303, 242606, 299186, 309960, 378014, 393208, 439105, 445795, 455182, 527078, 570021
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
Table of n, a(n) for n=1..33.
|
|
|
EXAMPLE
|
The sum of the distinct prime factors of 66 is 2 + 3 + 11 = 16; the sum of the distinct prime factors of 65 is 5 + 13 = 18; the sum of the distinct prime factors of 64 is 2; and 16 = 18 - 2. Hence 66 belongs to the sequence.
|
|
|
MATHEMATICA
|
p[n_] := Apply[Plus, Transpose[FactorInteger[n]][[1]]]; Select[Range[4, 10^5], p[ # ] == p[ # - 1] - p[ # - 2] &]
|
|
|
CROSSREFS
|
Cf. A008472, A075565, A075784, A075846, A076525, A076531, A076532, A076533.
Sequence in context: A121766 A052620 A052669 * A166815 A166797 A196453
Adjacent sequences: A076524 A076525 A076526 * A076528 A076529 A076530
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Oct 18 2002
|
|
|
EXTENSIONS
|
Edited and extended by Ray Chandler, Feb 13 2005
|
|
|
STATUS
|
approved
|
| |
|
|
