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 A094109 #7 Feb 17 2019 18:31:57 %S A094109 1,1,2,4,6,8,12,15,17,21,24,28,34,39,44,48,54,57,61,64,68,74,79,84,90, %T A094109 92,96,100,101,103,107,111,114,118,124,129,134,140,143,149,154,158, %U A094109 164,169,174,180,185,191,195,199,204,208,214,219,224,230,235,241 %N A094109 Start with "I" in Roman numerals (one). The next number (in Roman numerals) describes the number of Roman numerals written previously in the sequence. Convert this infinite sequence into an infinite sequence of Arabic numbers. %H A094109 Nathaniel Johnston, <a href="/A094109/b094109.txt">Table of n, a(n) for n = 1..573</a> %F A094109 a(n) = a(n-1) + A006968(a(n-1)) for n >= 3. - _Nathaniel Johnston_, May 18 2011 %e A094109 The sequence begins I, I, II, IV, VI, VIII, XII, XV, XVII, XXI, XXIV, XXVIII, XXXIV, XXIX, XLIII, XLVIII, LIV, LVII, LXI, LXIV, ... %p A094109 A094109 := proc(n) option remember: if(n<=2)then return 1:fi: return procname(n-1) + length(convert(procname(n-1),roman)): end: seq(A094109(n),n=1..58); # _Nathaniel Johnston_, May 18 2011 %Y A094109 See A006968 for how to spell the Roman numerals. %K A094109 nonn,base %O A094109 1,3 %A A094109 _Eric Angelini_, May 03 2004 %E A094109 Extended by _Nathaniel Johnston_, May 18 2011