313131

Appears in sequences

• Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 3,1.at n=5A037589
• Numbers that are divisible by all of their 1 and 2 digit substrings.at n=43A063527
• Triplets: base 10 representation is the juxtaposition of three identical strings.at n=30A074842
• Least multiple of n which is a repeated reverse concatenation of digits of n where n == 1, 3, 7 or 9 (mod 10).at n=5A110404
• Concatenation of segments of the digit sequence 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3 1 3....at n=5A137318
• List of imprimitive words over the alphabet {1,3}.at n=16A213973
• List of words over {1,3} with equal numbers of 1's and 3's.at n=22A214488
• Non-primitive words on {1,2,3}.at n=42A239018
• Number of oriented polyomino rings of length 4n with fourfold rotational symmetry.at n=19A324406
• Product of the smaller primes, p, in the Goldbach partitions of 2n such that p + q = 2n, p <= q, and p,q prime (or 1 if no Goldbach partition of 2n exists).at n=36A362641