The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A079008 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A079008

a(n) is smallest number k such that the n successive values of phi(k+j) (j=0,..,n-1) are all distinct.
(history; published version)

#14 by Joerg Arndt at Wed Feb 10 05:35:08 EST 2021

STATUS

reviewed

approved

#13 by Joerg Arndt at Wed Feb 10 05:34:54 EST 2021

STATUS

proposed

reviewed

#12 by Jinyuan Wang at Wed Feb 10 04:30:35 EST 2021

STATUS

editing

proposed

#11 by Jinyuan Wang at Wed Feb 10 04:29:36 EST 2021

MATHEMATICA

kul[x_] := Length[x]-Length[Union[x]] ; frt[x_] := Table[EulerPhi[x+j], {j, 0, h-1}] ; Table[fa=1; k=0; Do[s=fd1frt[n]; s1=kul[s]; If[Equal[s1, 0]&&Equal[fa, 1], k=k+1; Print[{k, n, h, EulerPhi[n], , s}]; fa=0], {n, 1, 10000}], {h, 1, 50}]

STATUS

approved

editing

Discussion

Wed Feb 10

04:30

Jinyuan Wang: added ";" so that prog can work now

#10 by Joerg Arndt at Wed Feb 10 02:02:19 EST 2021

STATUS

reviewed

approved

#9 by Michel Marcus at Wed Feb 10 01:55:45 EST 2021

STATUS

proposed

reviewed

#8 by Jinyuan Wang at Wed Feb 10 01:46:19 EST 2021

STATUS

editing

proposed

#7 by Jinyuan Wang at Wed Feb 10 01:46:12 EST 2021

NAME

a(n) = is smallest number k such that the n successive values of Phi[nphi(k+j] ) (j=0,..,n-1) are all distinct.

EXAMPLE

n=8: a(8)=37, values of phi[(k] ) for k=37,..,44 are: {36, 18, 24, 16, 40, 12, 42, 20}.

PROG

(PARI) a(n) = if(n==1, 1, my(v=vector(n, i, eulerphi(i))); for(k=n, oo, if(#Set(v)==n, return(k-n)); v[k%n+1]=eulerphi(k))); \\ Jinyuan Wang, Feb 10 2021

CROSSREFS

Cf. A079007, A048892, A079007, A079009.

STATUS

approved

editing

#6 by N. J. A. Sloane at Tue Oct 15 22:31:49 EDT 2013

AUTHOR

_Labos E. (labos(AT)ana.sote.hu), Elemer_, Jan 08 2003

Discussion

Tue Oct 15

22:31

OEIS Server: https://oeis.org/edit/global/2029

#5 by N. J. A. Sloane at Fri Feb 24 03:00:00 EST 2006

MATHEMATICA

kul[x_] := Length[x]-Length[Union[x]] frt[x_] := Table[EulerPhi[x+j], {j, 0, h-1}] Table[fa=1; k=0; Do[s=fd1[n]; s1=kul[s]; If[Equal[s1, 0]&&Equal[fa, 1], k=k+1; Print[{k, n, h, EulerPhi[n], s}]; fa=0], {n, 1, 10000}], {h, 1, 50}]

KEYWORD

nonn,new

nonn