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 A114807 #17 Jun 03 2025 17:56:40
%S A114807 315,632,551,23,409,516,383,655,352,621,431,48,575,419,430,316,777,
%T A114807 215,671,88,632,684,354,551,73,741,823,429,496,729,517,179,869,183,
%U A114807 687,194,767,352,748,779,69,431,99,511,627,775,439,804,651,110,317,592,186,44
%N A114807 The numbers 4^n-1 written in groups of three digits, with leading zeros omitted.
%H A114807 Harvey P. Dale, <a href="/A114807/b114807.txt">Table of n, a(n) for n = 1..1000</a>
%e A114807 3, 15, 63, 255, 1023, 4095, 16383, ...
%t A114807 FromDigits[#] & /@ Partition[ Flatten@ IntegerDigits@ Table[4^n - 1, {n, 22}], 3] (* _Robert G. Wilson v_, Jun 23 2014 *)
%t A114807 FromDigits/@Partition[Flatten[IntegerDigits/@(4^Range[30]-1)],3] (* _Harvey P. Dale_, Jun 03 2025 *)
%o A114807 (Python)
%o A114807 from itertools import count, islice
%o A114807 def bgen(): yield from (d for n in count(1) for d in str((1 << 2*n)-1))
%o A114807 def agen(): g = bgen(); yield from (int("".join(t)) for t in zip(g, g, g))
%o A114807 print(list(islice(agen(), 54))) # _Michael S. Branicky_, Dec 25 2022
%Y A114807 Cf. A114645, A114804, A114808, A114827.
%K A114807 base,dumb,nonn
%O A114807 1,1
%A A114807 _Jonathan Vos Post_, Feb 19 2006
%E A114807 a(4) and following changed by _Georg Fischer_, Dec 25 2022