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A073041 n*R(n)-1 is prime, where R(n) is reverse of n. 1
2, 12, 21, 30, 36, 60, 63, 90, 114, 132, 150, 162, 174, 192, 198, 204, 231, 237, 240, 246, 255, 261, 264, 291, 306, 330, 360, 378, 390, 402, 411, 420, 438, 447, 456, 462, 471, 477, 495, 510, 552, 588, 594, 603, 609, 627, 630, 642, 654, 669, 690, 726, 732 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
From Robert Israel, Jul 25 2019: (Start)
If n is in the sequence and is not divisible by 10, then A004086(n) is in the sequence.
All terms except 2 are divisible by 3. (End)
LINKS
EXAMPLE
12 is a term because 12*21-1=251 is prime.
MAPLE
revdigs:= proc(n) local L, i;
L:= convert(n, base, 10);
add(L[-i]*10^(i-1), i=1..nops(L))
end proc:
select(t -> isprime(t*revdigs(t)-1), [$1..1000]); # Robert Israel, Jul 25 2019
MATHEMATICA
Select[Range[800], PrimeQ[# IntegerReverse[#]-1]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 05 2020 *)
CROSSREFS
Sequence in context: A271361 A304813 A279424 * A284595 A053898 A058413
KEYWORD
easy,base,nonn
AUTHOR
Shyam Sunder Gupta, Aug 23 2002
STATUS
approved

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Last modified July 13 11:10 EDT 2024. Contains 374282 sequences. (Running on oeis4.)