23427

Appears in sequences

• Number of 5-leaf rooted trees with n levels.at n=17A007715
• Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 17.at n=8A031695
• Expansion of (1 + x)/(1 - 2*x - x^2 + x^3).at n=12A033303
• a(n) = A075443(A075451(n)).at n=31A075452
• Expansion of (1-x)/(1+2*x-x^2-x^3).at n=12A078056
• A Chebyshev transform of the Catalan numbers.at n=11A101499
• n+prime(n)+prime(prime(n)) is a triangular number, where prime(n) is the n-th prime.at n=21A116010
• Number of permutations of length n which avoid the patterns 123 and 4312.at n=26A116699
• a(n) = 289n^2 + 2n.at n=8A158254
• Partial sums of A029768.at n=8A174632
• Nonprime numbers with a sum of nonprime divisors which is a perfect square.at n=37A194580
• Number of n-length words on {1,2,3} such that the maximal blocks (runs) of 1's have odd length, the maximal blocks of 2's have even length and the maximal blocks of 3's have odd length.at n=14A242510
• Number of length n+1 0..2 arrays with at most one downstep in every n consecutive neighbor pairs.at n=15A255108
• 26-gonal pyramidal numbers: a(n) = n*(n+1)*(8*n-7)/2.at n=18A256646
• Maximal term of TRIP-Stern sequence of level n corresponding to permutation triple (e,13,e).at n=24A271485
• a(n) = binomial(n, 2) + 6*binomial(n, 4).at n=19A327319
• Integers which can be written in exactly three ways as sum of two distinct nonzero pentagonal numbers.at n=27A333013
• Coefficient of x^n in the expansion of ( 1/(1-x) * (1+x^3)^2 )^n.at n=8A370248