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 A303367 #10 May 07 2018 07:03:15 %S A303367 1,2,3,4,5,6,27,81,133,143,144,152,190,209,250,1125,8569,10934,16401, %T A303367 237568,362306,391257,695751,723260,5294625,6056974,6332291,6523631, %U A303367 6669475,11128547,12486285,17417491,18682225,19429514,19781014,20924092,21671381 %N A303367 Numbers equal to the determinant of a circulant matrix based on the base-7 digits of n. %C A303367 Base 7 variant of A219327. See A303366 .. A303369 for other bases. %e A303367 133 is in the sequence because 133 = 250[7] (in base 7) and 133 = det [2,5,0; 0,2,5; 5,0,2]. %o A303367 (PARI) (c(v)=abs(matdet(matrix(#v,#v,i,j,v[(j-i)%#v+1]))));for(n=1,oo,n==c(digits(n,7))&&print1(n",")) %Y A303367 Cf. A303366 (base 6), A303368 (base 8), A303369 (base 9), A219327 (base 10). %K A303367 nonn,base %O A303367 1,2 %A A303367 _M. F. Hasler_, May 05 2018 %E A303367 a(25)-a(37) from _Giovanni Resta_, May 07 2018