A019521 - OEIS

%I #52 Dec 30 2023 23:43:07

%S 1,14,149,14916,1491625,149162536,14916253649,1491625364964,

%T 149162536496481,149162536496481100,149162536496481100121,

%U 149162536496481100121144,149162536496481100121144169,149162536496481100121144169196,149162536496481100121144169196225

%N Concatenate squares.

%C a(3)=149 is the only prime up to n=4000. - _Daniel Arribas_, Jun 04 2016

%D S. Smarandoiu, Convergence of Smarandache continued fractions, Abstract 96T-11-195, Abstracts Amer. Math. Soc., Vol. 17, No. 4 (1996), p. 680.

%H Reinhard Zumkeller, <a href="/A019521/b019521.txt">Table of n, a(n) for n = 1..225</a>

%H Y. Guo and M. Le, <a href="http://vixra.org/abs/1403.0549">Smarandache Concatenated Power Decimals and Their Irrationality</a>, Smarandache Notions Journal, Vol. 9, No. 1-2 (1998), pp. 100-102.

%H F. Smarandache, <a href="http://www.gallup.unm.edu/~smarandache/CP2.pdf">Collected Papers, Vol. II</a>.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ConsecutiveNumberSequences.html">Consecutive Number Sequences</a>.

%p a:= proc(n) a(n):= `if`(n=1, 1, parse(cat(a(n-1), n^2))) end:

%p seq(a(n), n=1..20);  # _Alois P. Heinz_, Jan 13 2021

%o (Haskell)

%o a019521 n = a019521_list !! (n-1)

%o a019521_list = f "" $ tail a000290_list where

%o    f xs (q:qs) = (read ys :: Integer) : f ys qs

%o      where ys = xs ++ show q

%o -- _Reinhard Zumkeller_, Mar 01 2014

%o (Python)

%o def a(n): return int("".join(str(i*i) for i in range(1, n+1)))

%o print([a(n) for n in range(1, 16)]) # _Michael S. Branicky_, Jan 14 2021

%Y Cf. A000290, A007908, A038397.

%K base,nonn

%O 1,2

%A R. Muller