A050998 - cp's OEIS frontend

A050998 Inequivalent solutions to Langford (or Langford-Skolem) problem of arranging the numbers 1,1,2,2,3,3,...,n,n so that there is one number between the two 1's, two numbers between the two 2's, ..., n numbers between the two n's, listed by length and lexicographic order.

n	a(n)
1	231213
2	23421314
3	14156742352637
4	14167345236275
5	15146735423627
6	15163745326427
7	15167245236473
8	15173465324726
9	16135743625427
10	16172452634753
11	17125623475364
12	17126425374635
13	23627345161475

[231213, 23421314, 14156742352637, 14167345236275, 15146735423627, 15163745326427, 15167245236473, 15173465324726, 16135743625427, 16172452634753, 17125623475364, 17126425374635, 23627345161475]

cp's OEIS Frontend

A050998 Inequivalent solutions to Langford (or Langford-Skolem) problem of arranging the numbers 1,1,2,2,3,3,...,n,n so that there is one number between the two 1's, two numbers between the two 2's, ..., n numbers between the two n's, listed by length and lexicographic order.

Table of values

List of values