OFFSET
1,2
LINKS
Hans Havermann, Table of n, a(n) for n = 1..1000
EXAMPLE
one + ten = eleven (6 letters on both sides of the equal sign);
ten + two = twelve (6 letters on both sides);
two + twenty = twenty-two (9 letters on both sides);
twenty + three = twenty-three (11 letters on both sides);
three + thirty = thirty-three (11 letters on both sides);
thirty + four = thirty-four (10 letters on both sides);
four + nine = thirteen (8 letters on both sides);
nine + five = thirteen (8 letters on both sides); etc.
MATHEMATICA
len[n_]:=StringLength[StringReplace[IntegerName[n, "Words"], {" "-> "", ", "-> "", "-"-> ""}]]; a[1]=1;
a[n_]:=a[n]=Module[{m=First[Complement[Range[n], a/@Range[n-1]]]}, While[len[a[n-1]]+len[m]!=len[a[n-1]+m]||MemberQ[a/@Range[n-1], m]==True, m++]; m];
a/@Range[100] (* Ivan N. Ianakiev, Dec 14 2019 *)
CROSSREFS
KEYWORD
nonn,word
AUTHOR
Eric Angelini and Hans Havermann, Dec 12 2019
STATUS
approved