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 A045533 Concatenate the n-th and (n+1)st prime. 21

%I

%S 23,35,57,711,1113,1317,1719,1923,2329,2931,3137,3741,4143,4347,4753,

%T 5359,5961,6167,6771,7173,7379,7983,8389,8997,97101,101103,103107,

%U 107109,109113,113127,127131,131137

%N Concatenate the n-th and (n+1)st prime.

%H Reinhard Zumkeller, <a href="/A045533/b045533.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = prime(n)*(10^floor(log_10(prime(n+1)))+1) + prime(n+1). - _Conner L. Delahanty_, May 10 2014

%p P:=proc(i) local a,b,n; for n from 1 by 1 to i do a:=ithprime(n); b:=ithprime(n+1); a:=b+a*10^floor(evalf((log10(b)+1),100)); print(a); od; end: P(100); # _Paolo P. Lava_, Jan 21 2009

%t #[[1]]*10^IntegerLength[#[[2]]]+#[[2]]&/@Partition[Prime[Range[40]],2,1] (* _Harvey P. Dale_, Jun 06 2015 *)

%o a045533 n = a045533_list !! (n-1)

%o a045533_list = f \$ map show a000040_list :: [Integer] where

%o f (t:ts@(t':_)) = read (t ++ t') : f ts

%o -- _Reinhard Zumkeller_, Apr 20 2012

%o (PARI) a(n) = eval(concat(Str(prime(n)), Str(prime(n+1)))); \\ _Michel Marcus_, May 11 2014

%o (MAGMA) [Seqint(Intseq(NthPrime(n+1)) cat Intseq(NthPrime(n))): n in [1..50 ] ]; // _Marius A. Burtea_, Mar 21 2019

%Y Cf. A077800, A095958 (subsequence), A030461 (primes).

%K nonn,base

%O 1,1

%A _N. J. A. Sloane_, Dec 11 1999

%E Offset changed to 1, in agreement with (almost?) all references to this sequence, by _M. F. Hasler_

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Last modified August 14 19:42 EDT 2020. Contains 336483 sequences. (Running on oeis4.)