Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A109280
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
%I A109280
%S A109280 10,11,567,1209,2034,3114,3311,5243,5290,7256,7436,9558,10110,10111,
%T A109280 13251,14409,17536,20344,21534,26411,26816,29078,30232,34160,37074,
%U A109280 40022,44849,45373,45815,50630,53577,55555,56030,62355,62463,65540
%N A109280 Numbers n such that z(n) and z(n+1) are both prime, where z(n) = a^d 
               + b^d + c^d + ..., where a*b*c* ... is the prime factorization of 
               n and d is the largest digit of n.
%C A109280 Conjecture: Sequence is infinite.
%e A109280 567 is in the sequence because 567 = 3^4*7 and 3^7+3^7+3^7+3^7+7^7 = 
               832291,
%e A109280 a prime; and 568 = 2^3*71 and 2^8+2^8+2^8+71^8 = 645753531246529, a prime.
%Y A109280 Cf. A082813, A109279.
%Y A109280 Sequence in context: A041217 A041218 A041917 this_sequence A064841 A064795 
               A078285
%Y A109280 Adjacent sequences: A109277 A109278 A109279 this_sequence A109281 A109282 
               A109283
%K A109280 base,nonn
%O A109280 1,1
%A A109280 Jason Earls (zevi_35711(AT)yahoo.com), Jun 24 2005

    
page 1

Search completed in 0.002 seconds

Lookup | Welcome | Find friends | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
More pages | Superseeker | Maintained by N. J. A. Sloane (njas@research.att.com)

Last modified November 27 22:38 EST 2009. Contains 167602 sequences.


AT&T Labs Research