23220

Appears in sequences

• a(n) = ceiling(10000*log_2(n)).at n=4A004270
• Bishops on an n X n board (see Robinson paper for details).at n=8A005634
• Expansion of sum ( q^n / product( 1-q^k, k=1..6*n), n=0..inf ).at n=31A035298
• Smallest triangular number containing exactly n 2's.at n=2A036519
• a(n) = (2*n - 1)*(7*n^2 - 7*n + 6)/6.at n=21A063490
• Triangular numbers of the form 10*k.at n=42A069498
• Triangular numbers which are 7-almost primes.at n=12A076581
• Third row of Pascal-(1,6,1) array A081581.at n=31A081591
• Triangular numbers whose sum of divisors is also a triangular number.at n=3A083674
• Sequence A014486 shown in base 4.at n=35A085185
• a(n) = A000217(n^3) - n^3.at n=6A085744
• Triangular numbers whose sum of squared digits is also triangular.at n=15A094890
• Triangular numbers equal to the sum of a prime number with its index.at n=19A115886
• Triangular numbers for which the sum of the digits is a square.at n=21A117404
• Hexagonal numbers divisible by 6.at n=36A117794
• Triangular numbers composed of digits {0,2,3}.at n=3A119049
• Triangle read by rows: row n is the first row of the matrix M[n]^(n-1), where M[n] is the n X n tridiagonal matrix with main diagonal (1,4,4,...) and super- and subdiagonals (1,1,1,...).at n=50A124576
• A123689 based sequence as SO(A123689(n)) dimensions.at n=16A131513
• Number of 4-way intersections in the interior of a regular 6n-gon.at n=29A137938
• a(1) = 1, a(2) = 3, a(n+2) = 3*a(n+1) + (n+1)^2*a(n).at n=6A142979