The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A178555 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A178555

Primes with exactly six 6's.
(history; published version)

#12 by OEIS Server at Tue May 08 08:00:43 EDT 2018

LINKS

Robert Israel, <a href="/A178555/b178555_1.txt">Table of n, a(n) for n = 1..10000</a>

#11 by N. J. A. Sloane at Tue May 08 08:00:43 EDT 2018

STATUS

proposed

approved

Discussion

Tue May 08

08:00

OEIS Server: Installed new b-file as b178555.txt.  Old b-file is now b178555_1.txt.

#10 by Bruno Berselli at Tue May 08 06:21:44 EDT 2018

STATUS

editing

proposed

#9 by Bruno Berselli at Tue May 08 06:21:15 EDT 2018

KEYWORD

nonn,base,look,changed

STATUS

proposed

editing

#8 by David A. Corneth at Tue May 08 05:22:39 EDT 2018

STATUS

editing

proposed

#7 by David A. Corneth at Tue May 08 05:22:36 EDT 2018

CROSSREFS

Cf. A038618, A178550-4, A178554, A178556-8A178558.

STATUS

proposed

editing

#6 by Robert Israel at Tue May 08 05:11:33 EDT 2018

STATUS

editing

proposed

Discussion

Tue May 08

05:22

David A. Corneth: Keyword: look?

#5 by Robert Israel at Tue May 08 05:11:14 EDT 2018

LINKS

Robert Israel, <a href="/A178555/b178555_1.txt">Table of n, a(n) for n = 1..10000</a>

MAPLE

if L[-1] = 0 then next fi;

STATUS

proposed

editing

#4 by Robert Israel at Tue May 08 05:05:59 EDT 2018

STATUS

editing

proposed

#3 by Robert Israel at Tue May 08 05:05:50 EDT 2018

LINKS

Robert Israel, <a href="/A178555/b178555.txt">Table of n, a(n) for n = 1..10000</a>

MAPLE

f:= proc(m) local R, L, s, k, t, x;

R:= NULL;

for k from 9^(m-6) to 2*9^(m-6)-1 do

t:= Vector(subs([8=9, 7=8, 6=7], convert(k, base, 9)[1..m-6]));

for s in combinat:-choose([$2..m], m-7) do

L:= Vector(m, 6);

L[[1, op(s)]]:= t;

x:= add(L[i]*10^(i-1), i=1..m);

if isprime(x) then R:= R, x fi;

od od:

op(sort([R]));

end proc:

f(8); # Robert Israel, May 08 2018

STATUS

approved

editing