|
Search: id:A060845
|
|
|
| A060845 |
|
Largest prime < a nontrivial power of a prime. |
|
+0
2
|
|
| 3, 7, 7, 13, 23, 23, 31, 47, 61, 79, 113, 113, 127, 167, 241, 251, 283, 337, 359, 509, 523, 619, 727, 839, 953, 1021, 1327, 1367, 1669, 1847, 2039, 2179, 2179, 2207, 2399, 2803, 3121, 3469, 3719, 4093, 4483, 4909, 5039, 5323, 6229, 6553, 6857, 6883, 7919
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
Harry J. Smith, Table of n, a(n) for n=1,...,1000
|
|
FORMULA
|
a(n) = prevprime[A025475(n)] = A007917[A025475(n)] = Max{p| p<A025475(n)}
|
|
EXAMPLE
|
78125=5^7 follows 78121
|
|
PROGRAM
|
(PARI) { m=1; for (n=1, 1000, m++; while(sigma(m)*eulerphi(m)*(1 - isprime(m)) <= (m - 1)^2, m++); write("b060845.txt", n, " ", precprime(m - 1)); ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 19 2009]
|
|
CROSSREFS
|
Cf. A025475, A000961, A001597, A001694, A007917, A007918, A013632, A013633, A049711, A060846.
Sequence in context: A137315 A139795 A118259 this_sequence A060215 A059478 A081218
Adjacent sequences: A060842 A060843 A060844 this_sequence A060846 A060847 A060848
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), May 03 2001
|
|
|
Search completed in 0.002 seconds
|
