20701

Appears in sequences

• Strong pseudoprimes to base 59.at n=19A020285
• Expansion of 1/((1-x)(1-3x)(1-6x)(1-8x)).at n=4A021503
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 94 ones.at n=22A031862
• Long leg of primitive Pythagorean triangles having legs that add up to a square, sorted on hypotenuse.at n=20A089548
• Numerators of the difference between the squarefree totient analogs of the harmonic numbers and the harmonic numbers: F_n-H_n.at n=10A138320
• Ulam's spiral (NNW spoke).at n=36A143860
• a(n) = 900*n + 1.at n=22A158407
• Numbers k such that Sum_{i=1..k} i^7 divides Product_{i=1..k} i^7.at n=20A166607
• Number of ways to connect with nonintersecting chords n unlabeled points equally spaced on a circle such that the resulting configuration is not invariant w.r.t. rotation any angle < 2*Pi.at n=14A175955
• a(n) = 6*n^3 - 263*n^2 + 3469*n - 12841.at n=31A218457
• Number of paths joining opposite corners of an n X 2 grid with every vertex appearing at most twice in the path.at n=4A239688
• Number of times prime(n) occurs as the least prime factor among numbers 1 .. prime(n)^4: a(n) = A078898(A030514(n)).at n=15A250478
• Quasi-Carmichael numbers to exactly two bases.at n=36A257752
• Number of set partitions of [n] into subsets whose element sums are distinct squares.at n=17A278339
• Total sum of the left-to-right maxima in all compositions of n into distinct parts.at n=20A336771
• Number of genetic relatives of a person M in a genealogical tree extending back n generations and where everyone has 7 children down to the generation of M.at n=4A358601
• E.g.f. satisfies A(x) = exp( x/(1 - x/A(x)^3) ).at n=6A361092
• Centered pentachoral numbers.at n=9A365205