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 A180597 #19 Sep 25 2022 10:28:47 %S A180597 0,7,5,3,1,8,6,4,2,9,7,5,3,1,8,6,4,2,9,7,5,3,1,8,6,4,2,9,7,5,3,1,8,6, %T A180597 4,2,9,7,5,3,1,8,6,4,2,9,7,5,3,1,8,6,4,2,9,7,5,3,1,8,6,4,2,9,7,5,3,1, %U A180597 8,6,4,2,9,7,5,3,1,8,6,4,2,9,7,5,3,1,8,6,4,2,9,7,5,3,1,8,6,4,2,9,7,5,3,1,8 %N A180597 Digital root of 7n. %C A180597 Period of 9. - _Robert G. Wilson v_, Sep 20 2010 %H A180597 <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,1). %F A180597 G.f.: x*(7 + 5*x + 3*x^2 + x^3 + 8*x^4 + 6*x^5 + 4*x^6 + 2*x^7 + 9*x^8)/(1 - x^9). - _Stefano Spezia_, Apr 21 2022 %F A180597 a(n) = A010888(A008589(n)). - _Michel Marcus_, Apr 21 2022 %t A180597 f[n_] := Mod[7 n - 1, 9] + 1; f[0] = 0; Array[f, 105, 0] (* _Robert G. Wilson v_, Sep 20 2010 *) %o A180597 (PARI) a(n)=7*n%9 \\ _Charles R Greathouse IV_, Aug 22 2014 %Y A180597 Cf. A010888, A008589. %Y A180597 Cf. A180592, A180594, A180595, A180596, A180592, A180593, A180594, A180595, A180596, A180598, A180599. %Y A180597 Column k = 7 in A353109. %K A180597 easy,nonn,base %O A180597 0,2 %A A180597 _Odimar Fabeny_, Sep 10 2010 %E A180597 More terms from _Robert G. Wilson v_, Sep 20 2010