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A224827
Primes p such that prime(floor(p/10) + (p mod 10)) = p.
1
64279, 64319, 64483, 64513, 64621
OFFSET
1,1
COMMENTS
Subset of A224843. Sequence is clearly finite, since the ratio prime(n)/n is unbounded. By comparing prime(x/10) with x and using suitable functions which provide upper and lower bounds for prime(x), it is also possible to infer that no more terms exist. - Giovanni Resta, Jul 22 2013
LINKS
Chris K. Caldwell and G. L. Honaker, Jr., Prime Curios! 64621
EXAMPLE
prime(6462+1) = 64621 which is prime. Hence, 64621 is in sequence.
MAPLE
with(numtheory):KD := proc(p)
ithprime((p-(p mod 10))/10 + (p mod 10))=p ;
end proc:
for p from 1 to 65000 do
if KD(p) then
printf("%d, ", p) ;
end if;
end do:# K. D. Bajpai, Jul 21 2013
with(numtheory):K:=proc()local n, a, c, p; p:=3; c:=1; for n from 1 to 50000 do; p:=ithprime(n); a:= ithprime((p-(p mod 10))/10 + (p mod 10)); if p=a then lprint(c, p); c:=c+1; fi; od; end: K(); # K. D. Bajpai, Jul 21 2013
PROG
(PARI) is(p)=p==prime(p\10+p%10)&&isprime(p) \\ Charles R Greathouse IV, Jul 22 2013
CROSSREFS
Cf. A224843.
Sequence in context: A031859 A182811 A236702 * A234128 A205631 A205333
KEYWORD
nonn,base,fini,full
AUTHOR
K. D. Bajpai, Jul 21 2013
STATUS
approved