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A068698 Smallest primes in the reverse concatenation of n consecutive odd numbers. 0
3, 31, 0, 59575553, 15131197, 0, 55535149474543, 6361595755535149, 0, 1151131111091071051031019997, 207205203201199197195193191189187, 0, 65636159575553514947454341, 4543413937353331292725232119, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
a(5) = 15131197 is a prime and a concatenation of 15,13,11,9 and 7.
MAPLE
for n from 1 to 32 do d := 0:c := true: if((n mod 3)=0) then c := false:a := 0:end if: while(c=true) do a := 2*(n+d)-1:for j from 1 to n-1 do a := 2*(n+d-j)-1+10^( floor(evalf(log(2*(n+d-j)-1)/log(10))+0.0000000001 )+1)*a:end do: if(isprime(a))then c := false:end if:d := d+1:end do:b[n] := a:end do:seq(b[h], h=1..32);
CROSSREFS
Sequence in context: A155731 A145385 A059232 * A053300 A322777 A089281
KEYWORD
base,hard,nonn
AUTHOR
Amarnath Murthy, Mar 04 2002
EXTENSIONS
More terms from Sascha Kurz, Mar 27 2002
Definition clarified by Harvey P. Dale, Dec 25 2022
STATUS
approved

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Last modified July 13 18:54 EDT 2024. Contains 374285 sequences. (Running on oeis4.)