login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A057609 Powers of a prime lucky number (A031157) but excluding lucky numbers (A000959). 0
27, 81, 243, 343, 1849, 2197, 2401, 4489, 5329, 6241, 6561, 16807, 16807, 19683, 22801, 26569, 28561, 37249, 44521, 59049, 79507, 117649, 177147, 371293, 531441, 1594323 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Up to 10^7, terms are 3^3, 3^4, 3^5, 3^8, 3^9, 3^10, 3^11, 3^12, 3^13, 7^3, 7^4, 7^5, 7^6, 13^3, 13^4, 13^5, 43^2, 43^3, 67^2, 73^2, 79^2, 127^2, 151^2, 163^2, 193^2, 211^2, ..., . - Robert G. Wilson v, May 12 2006

LINKS

Table of n, a(n) for n=1..26.

EXAMPLE

In the first 23 terms of A000959, {1, 3, 7, 9, 13, 15, 21, 25, 31, 33, 37, 43, 49, 51, 63, 67, 69, 73, 75, 79, 87, 93, 99}, 3 is a prime lucky number (A031157), and 3^2 is also a lucky number, but 3^3=27 and 3^4=81 are not lucky numbers, so they are terms of this sequence.

MATHEMATICA

lst = Range[1, 2*10^7, 2]; i = 2; While[i <= (len = Length[lst]) && (k = lst[[i]]) <= len, lst = Drop[lst, {k, len, k}]; i++ ]; p = Select[lst, PrimeQ@# &]; lst2 = {}; Do[k = 1; lmt = Floor@Log[ p[[n]], 10^7]; t = Table[p[[n]]^i, {i, 2, lmt}]; While[k < lmt - 1, If[ !MemberQ[lst, t[[k]] ], AppendTo[lst2, t[[k]] ]]; k++ ], {n, Length@p}]; Sort@lst2 (* Robert G. Wilson v, May 12 2006 *)

CROSSREFS

Cf. A031157, A000959.

Sequence in context: A215782 A216438 A292872 * A255624 A008884 A031455

Adjacent sequences:  A057606 A057607 A057608 * A057610 A057611 A057612

KEYWORD

more,nonn

AUTHOR

Naohiro Nomoto, Oct 09 2000

EXTENSIONS

More terms from Robert G. Wilson v, May 12 2006

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 24 11:34 EDT 2019. Contains 321448 sequences. (Running on oeis4.)