Svoboda | Graniru | BBC Russia | Golosameriki | Facebook
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A249224 Lpf (n(n+11)/2): least prime dividing n(n+11)/2. 1
2, 13, 3, 2, 2, 3, 3, 2, 2, 3, 11, 2, 2, 5, 3, 2, 2, 3, 3, 2, 2, 3, 17, 2, 2, 13, 3, 2, 2, 3, 3, 2, 2, 3, 5, 2, 2, 7, 3, 2, 2, 3, 3, 2, 2, 3, 29, 2, 2, 5, 3, 2, 2, 3, 3, 2, 2, 3, 5, 2, 2, 31, 3, 2, 2, 3, 3, 2, 2, 3, 41, 2, 2, 5, 3, 2, 2, 3, 3, 2, 2, 3, 47, 2, 2, 43, 3, 2, 2, 3, 3, 2, 2, 3, 5, 2, 2, 7, 3, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(n) = 2 for n = {4,5,8,9} (mod 12) and a(n) = 3 for n = {3,6,7,10} (mod 12).
LINKS
FORMULA
a(n) = A020639(n(n+11)/2).
MATHEMATICA
FactorInteger[#(11+#)/2][[1, 1]]& /@ Range[100]
PROG
(PARI) a(n) = my(f=factor(n*(n+11)/2)); f[1, 1]; \\ Michel Marcus, Oct 23 2014
CROSSREFS
Sequence in context: A090954 A089778 A088253 * A217010 A091023 A337838
KEYWORD
nonn,easy
AUTHOR
Zak Seidov, Oct 23 2014
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 12 01:49 EDT 2024. Contains 375842 sequences. (Running on oeis4.)