A038394 Concatenate first n primes in reverse order.

2, 32, 532, 7532, 117532, 13117532, 1713117532, 191713117532, 23191713117532, 2923191713117532, 312923191713117532, 37312923191713117532, 4137312923191713117532, 434137312923191713117532, 47434137312923191713117532, 5347434137312923191713117532

Offset: 1

Author

M. I. Petrescu (mipetrescu(AT)yahoo.com)

Keywords

• nonn
• base

References

• F. Smarandache, Sequences of Numbers Involved in Unsolved Problems, Hexis, Phoenix, 2006.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..300
• Mihaly Bencze [Beneze] and L. Tutescu, editors, Some Notions and Questions in Number Theory, Vol. II.
• M. Fleuren, Smarandache Back Concatenated Primes.
• F. Smarandache, Sequences of Numbers Involved in Unsolved Problems.

Crossrefs

Cf. A000040, A000422, A019518.

Programs

Haskell

a038394 n = a038394_list !! (n-1)
a038394_list = f "" a000040_list where
   f xs (q:qs) = (read ys :: Integer) : f ys qs
     where ys = show q ++ xs
-- Reinhard Zumkeller, Mar 03 2014

Mathematica

Join[{s = 2}, Table[s = FromDigits[Flatten[IntegerDigits[{Prime[n], s}]]], {n, 2, 13}]] (* Jayanta Basu, Jul 14 2013 *)

PARI

a(n) = fromdigits(concat([digits(p) | p<-Vecrev(primes(n))])); \\ Andrew Howroyd, Aug 29 2020

Extensions

Offset corrected by Reinhard Zumkeller, Mar 03 2014