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.

1, 49, 162, 5364, 96481, 100121, 1441691, 96225256, 289324361, 4004414845, 29576625676, 729784841900, 9611024108911, 56122512961369, 144415211600168, 1176418491936202, 52116220923042401, 250026012704280929, 1630253136324933643, 48136003721384439694, 96422543564489462447

Offset: 1

Author

Amarnath Murthy, Dec 16 2001

Keywords

• nonn
• base

Comments

Are there any squares in this sequence other than 1 and 49?

No other squares in a(3)..a(10^5). - Michael S. Branicky, May 23 2025

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A066547, A066549.

Programs

Mathematica

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 *)

Python

from itertools import count, islice
def agen(): # generator of terms
    N, i = [], 1
    for n in count(1):
        target = n*(n-1)//2
        while len(N) <= target+n+1:
            N.extend(list(str(i**2)))
            i += 1
        yield int("".join(N[target:target+n]))
print(list(islice(agen(), 21))) # Michael S. Branicky, May 23 2025

Extensions

Corrected and extended by Lior Manor, Feb 13 2002

a(19) and beyond from Michael S. Branicky, May 23 2025