

A052999


Take nth prime p, let P(p) = all primes that can be obtained by permuting the digits of p and possibly adding or omitting zeros; a(n) = pq where q in P(p) is the closest to p but different from p (a(n)=0 if no such q exists).


5



0, 0, 0, 0, 90, 18, 54, 90, 1980, 199980, 18, 36, 360, 3960, 3960, 450, 450, 540, 540, 36, 36, 18, 79999999999999999999999999999920, 720, 18, 90, 72, 36, 90, 18, 144, 18, 36, 54, 270, 900, 414, 450, 450, 36, 18, 630, 720, 54, 18, 720, 810, 1980, 1800, 1800, 2790, 54, 180, 270, 20250, 1800, 1800, 144
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OFFSET

1,5


COMMENTS

Conjecture: a(n) > 0 for n > 4.  Sean A. Irvine, Nov 23 2021


LINKS

Table of n, a(n) for n=1..58.


EXAMPLE

a(6)=18 since 6th prime is 13 and 3113=18. a(9)=1980 because 9th prime is 23 and the smallest prime in P(6) different from 23 is 2003; 200323=1980.
a(23)=(8*10^31+3)83 because 8*10^31+3 is closest prime distinct from 83 but in P(83).  Sean A. Irvine, Nov 23 2021


CROSSREFS

Cf. A052902, A052998, A053544, A052495, A052484.
Sequence in context: A078293 A247899 A247902 * A050662 A236180 A332427
Adjacent sequences: A052996 A052997 A052998 * A053000 A053001 A053002


KEYWORD

base,easy,nonn


AUTHOR

N. J. A. Sloane, Mar 16 2000


EXTENSIONS

More terms from Asher Natan Auel (auela(AT)reed.edu), May 12, 2000
a(23) corrected by Sean A. Irvine, Nov 23 2021


STATUS

approved



