|
Search: id:A125296
|
|
|
| A125296 |
|
a(1)=1. a(n) is the number of earlier terms of the sequence which are noncomposites (1 or primes) and are coprime to n. |
|
+0
1
|
|
| 1, 1, 2, 2, 4, 2, 5, 3, 6, 3, 8, 3, 9, 6, 5, 7, 11, 6, 12, 7, 8, 9, 13, 8, 12, 10, 11, 10, 15, 7, 16, 13, 12, 14, 12, 11, 18, 15, 13, 14, 19, 11, 21, 14, 16, 18, 21, 15, 18, 16, 18, 15, 21, 15, 15, 15, 17, 19, 23, 16, 24, 21, 18, 21, 19, 15, 25, 21, 21, 17, 26, 20, 26, 23, 22, 21, 20
(list; graph; listen)
|
|
|
OFFSET
|
1,3
|
|
|
EXAMPLE
|
The noncomposites among the first 7 terms of the sequence are 1,1,2,2,2,5. Of these, three terms (1,1,5) are coprime to 8. So a(8)=3.
|
|
MATHEMATICA
|
f[l_List] := Append[l, Length[Select[l, GCD[ #, Length[l] + 1] == 1 && (PrimeQ[ # ] || # == 1) &]]]; Nest[f, {1}, 80] (*Chandler*)
|
|
CROSSREFS
|
Sequence in context: A057567 A005128 A129296 this_sequence A121895 A139555 A088371
Adjacent sequences: A125293 A125294 A125295 this_sequence A125297 A125298 A125299
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Leroy Quet (qq-quet(AT)mindspring.com), Dec 08 2006
|
|
EXTENSIONS
|
Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Dec 11 2006
|
|
|
Search completed in 0.002 seconds
|
