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%I #30 Feb 17 2024 10:30:47
%S 2,32,532,7532,117532,13117532,1713117532,191713117532,23191713117532,
%T 2923191713117532,312923191713117532,37312923191713117532,
%U 4137312923191713117532,434137312923191713117532,47434137312923191713117532,5347434137312923191713117532
%N Concatenate first n primes in reverse order.
%D F. Smarandache, Sequences of Numbers Involved in Unsolved Problems, Hexis, Phoenix, 2006.
%H Reinhard Zumkeller, <a href="/A038394/b038394.txt">Table of n, a(n) for n = 1..300</a>
%H Mihaly Bencze [Beneze] and L. Tutescu, editors, <a href="http://www.gallup.unm.edu/~smarandache/snaqint2.txt">Some Notions and Questions in Number Theory, Vol. II</a>.
%H M. Fleuren, <a href="http://www.gallup.unm.edu/~smarandache/SmBackConPri.txt">Smarandache Back Concatenated Primes</a>.
%H F. Smarandache, <a href="http://www.gallup.unm.edu/~smarandache/Sequences-book.pdf">Sequences of Numbers Involved in Unsolved Problems</a>.
%t Join[{s = 2}, Table[s = FromDigits[Flatten[IntegerDigits[{Prime[n], s}]]], {n, 2, 13}]] (* _Jayanta Basu_, Jul 14 2013 *)
%o (Haskell)
%o a038394 n = a038394_list !! (n-1)
%o a038394_list = f "" a000040_list where
%o f xs (q:qs) = (read ys :: Integer) : f ys qs
%o where ys = show q ++ xs
%o -- _Reinhard Zumkeller_, Mar 03 2014
%o (PARI) a(n) = fromdigits(concat([digits(p) | p<-Vecrev(primes(n))])); \\ _Andrew Howroyd_, Aug 29 2020
%Y Cf. A000040, A000422, A019518.
%K nonn,base
%O 1,1
%A M. I. Petrescu (mipetrescu(AT)yahoo.com)
%E Offset corrected by _Reinhard Zumkeller_, Mar 03 2014
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