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A066551 Let N =149162536496481100121441691962252562893243614..., the concatenation of the squares. a(n) is the n-digit number formed from the digits of N starting from the {n(n-1)/2 +1}th digit. Omit any leading zeros.

%I A066551 #18 May 23 2025 16:07:57
%S A066551 1,49,162,5364,96481,100121,1441691,96225256,289324361,4004414845,
%T A066551 29576625676,729784841900,9611024108911,56122512961369,
%U A066551 144415211600168,1176418491936202,52116220923042401,250026012704280929,1630253136324933643,48136003721384439694,96422543564489462447
%N A066551 Let N =149162536496481100121441691962252562893243614..., the concatenation of the squares. a(n) is the n-digit number formed from the digits of N starting from the {n(n-1)/2 +1}th digit. Omit any leading zeros.
%C A066551 Are there any squares in this sequence other than 1 and 49?
%C A066551 No other squares in a(3)..a(10^5). - _Michael S. Branicky_, May 23 2025
%H A066551 Michael S. Branicky, <a href="/A066551/b066551.txt">Table of n, a(n) for n = 1..1000</a>
%t A066551 With[{c=Flatten[IntegerDigits/@(Range[100]^2)]},Table[FromDigits[Take[c,{(n(n-1))/2+1,(n(n-1))/2+n}]],{n,20}]] (* _Harvey P. Dale_, Jul 21 2012 *)
%o A066551 (Python)
%o A066551 from itertools import count, islice
%o A066551 def agen(): # generator of terms
%o A066551     N, i = [], 1
%o A066551     for n in count(1):
%o A066551         target = n*(n-1)//2
%o A066551         while len(N) <= target+n+1:
%o A066551             N.extend(list(str(i**2)))
%o A066551             i += 1
%o A066551         yield int("".join(N[target:target+n]))
%o A066551 print(list(islice(agen(), 21))) # _Michael S. Branicky_, May 23 2025
%Y A066551 Cf. A066547, A066549.
%K A066551 nonn,base
%O A066551 1,2
%A A066551 _Amarnath Murthy_, Dec 16 2001
%E A066551 Corrected and extended by _Lior Manor_, Feb 13 2002
%E A066551 a(19) and beyond from _Michael S. Branicky_, May 23 2025