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 A303369 #12 May 07 2018 07:22:34 %S A303369 1,2,3,4,5,6,7,8,104,126,130,468,2035,8052,8421,12100,18788,21296, %T A303369 60736,90155,109135,119795,123201,137605,147095,160965,199728,457856, %U A303369 523809,697334,2958176,3652360,4725030,5331625,6825024,7014400,7694336,9376133,14012352 %N A303369 Numbers equal to the determinant of a circulant matrix based on the base-9 digits of n. %C A303369 Base 9 variant of A219327. See A303366 .. A303368 for other bases. %e A303369 104 is in the sequence because 104 = 125[9] (in base 9) and 104 = det [1,2,5; 5,1,2; 2,5,1]. %o A303369 (PARI) (c(v)=abs(matdet(matrix(#v,#v,i,j,v[(j-i)%#v+1]))));for(n=1,oo,n==c(digits(n,9))&&print1(n",")) %Y A303369 Cf. A303366 (base 6), A303367 (base 7), A303368 (base 8), A219327 (base 10). %K A303369 nonn,base %O A303369 1,2 %A A303369 _M. F. Hasler_, May 05 2018 %E A303369 a(31)-a(39) from _Giovanni Resta_, May 07 2018