231231

Appears in sequences

• Odd pentagonal pyramidal numbers.at n=19A015223
• Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 2,3,1.at n=5A037645
• Triangle of Stirling numbers of order 4.at n=20A059023
• Integers are written in the form abcd...n where "a" means "At position a in this integer there is a digit b"; "b" means: "at position b there is a digit c"; "c" means: "at position c there is a digit d"; ... and "n" means: "at position n there is a digit a".at n=26A105956
• Denominators of rationals related to John Wallis' product formula for Pi/2 (from his 'Arithmetica infinitorum' from 1659).at n=5A120995
• a(n) is the smallest number not already in the sequence, such that the concatenation of all a(n) displays the periodic digit string 1, 2, 3 (and repeat).at n=17A165301
• Triangle read by rows, the coefficients of J. L. Fields generalized Bernoulli polynomials.at n=32A220412
• Non-primitive words on {1,2,3}.at n=36A239018