This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A138821 #21 Sep 08 2022 08:45:33
%S A138821 12,13,25,37,511,813,1317,2119,3423,5529,8931,14437,23341,37743,61047,
%T A138821 98753,159759,258461,418167,676571,1094673,1771179,2865783,4636889,
%U A138821 7502597,121393101,196418103,317811107,514229109,832040113,1346269127
%N A138821 Concatenation of n-th Fibonacci number and n-th prime.
%H A138821 Harvey P. Dale, <a href="/A138821/b138821.txt">Table of n, a(n) for n = 1..1000</a>
%e A138821 a(10)=5529 because A000045(10)=55 and A000040(10)=29.
%p A138821 f:= proc(n) local p;
%p A138821 p:= ithprime(n);
%p A138821 combinat:-fibonacci(n)*10^(1+ilog10(p))+p
%p A138821 end proc:
%p A138821 seq(f(n),n=1..100); # _Robert Israel_, Dec 15 2014
%t A138821 With[{nn=40},FromDigits[Flatten[IntegerDigits/@#]]&/@ Thread[ {Fibonacci[ Range[nn]],Prime[Range[nn]]}]] (* _Harvey P. Dale_, Dec 23 2011 *)
%o A138821 (Magma) [Seqint(Intseq(NthPrime(n)) cat Intseq(Fibonacci(n))): n in [1..50]]; // _Vincenzo Librandi_, Jul 24 2019
%Y A138821 Cf. A000040, A000045, A045532, A075110.
%K A138821 base,easy,nonn
%O A138821 1,1
%A A138821 _Omar E. Pol_, Apr 05 2008, Apr 07 2008