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A216418
Fortunate numbers with increasing multiplicity.
0
3, 23, 61, 331, 2837, 18169
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OFFSET
1,1
COMMENTS
a(n) appears in
A005235
more often than any preceding term.
Is this sequence infinite?
LINKS
Table of n, a(n) for n=1..6.
EXAMPLE
3 is the first term of
A005235
, so a(1) = 3.
A005235
(5) =
A005235
(8) = 23, while smaller primes appear only once, so a(2) = 23.
PROG
(PARI) ct(p)=my(pr=1, s); forprime(q=2, p-1, if(!ispseudoprime((pr*=q)+p), next); forprime(r=q+1, p-1, if(ispseudoprime(pr+r), next(2))); s++); s
r=0; forprime(p=2, 2e3, t=ct(p); if(t>r, r=t; print1(p", ")))
CROSSREFS
Cf.
A005235
,
A046066
.
Sequence in context:
A232193
A141047
A196538
*
A254626
A362540
A262769
Adjacent sequences:
A216415
A216416
A216417
*
A216419
A216420
A216421
KEYWORD
nonn
,
hard
,
more
AUTHOR
Charles R Greathouse IV
, Sep 06 2012
EXTENSIONS
a(6) from
Charles R Greathouse IV
, Sep 17 2012
STATUS
approved
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Last modified September 6 22:26 EDT 2024. Contains 375728 sequences. (Running on oeis4.)