cp's OEIS Frontend

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.

A376897 Positive numbers k such that all the digits in the octal expansion of k^2 are distinct.

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%I A376897 #19 Oct 12 2024 22:32:50
%S A376897 1,2,4,5,7,13,14,15,18,20,21,28,30,37,39,43,44,45,53,55,63,78,84,103,
%T A376897 110,113,117,127,149,155,156,161,162,172,173,174,175,179,220,236,242,
%U A376897 270,286,293,299,301,340,343,350,356,361,395,407,412,425,439,461,475,499,674,819,1001,1211,1230,1244,1323,1764,2450,2751,3213
%N A376897 Positive numbers k such that all the digits in the octal expansion of k^2 are distinct.
%C A376897 There are no terms >= 2^12 because 2^24-1 is the largest eight-digit octal number.
%e A376897 110 is in the sequence because 110^2 = 12100 = 27504_8 and no octal digit occurs more than once.
%t A376897 Select[Range[2^12], DuplicateFreeQ[IntegerDigits[#^2, 8]] &] (* _Michael De Vlieger_, Oct 12 2024 *)
%o A376897 (Python)
%o A376897 for k in range(1, 2**12):
%o A376897     octal = format(k**2, "o")
%o A376897     if len(octal) == len(set(octal)): print(k, end=",")
%Y A376897 Cf. A007094, A119509, A376898.
%K A376897 base,fini,full,nonn
%O A376897 1,2
%A A376897 _Kalle Siukola_, Oct 08 2024