21170

Appears in sequences

• Number of points on surface of hexagonal prism: 12*n^2 + 2 for n > 0 (coordination sequence for W(2)).at n=42A005914
• a(0) = 1, a(n) = 27*n^2 + 2 for n>0.at n=28A010017
• a(n) = n*(n+1)*(5*n+1)/6.at n=28A033994
• Fibonacci iteration starting with (1, a(n)) leads to a "nine digits anagram".at n=34A034587
• Dirichlet convolution of phi(n) with Bell numbers.at n=9A034767
• Numbers k such that |s(k) - k| = number of primes <= k, where s(k) is sigma(k) - k.at n=7A037175
• Base 9 digits are, in order, the first n terms of the periodic sequence with initial period 3,2,0.at n=4A037672
• Even numbers seen in decimal expansion of Pi (disregarding the decimal period) contiguous, smallest and distinct.at n=33A050818
• Number of n-celled polyominoes without holes, symmetric about axis 2.at n=37A056880
• Deficient oblong numbers.at n=24A077804
• Pseudo-random numbers: Davenport's generator for 32-bit integers.at n=29A084277
• a(n) = (4*n+1)*(4*n+2) = (4*n+2)!/(4*n)!.at n=36A157870
• Expansion of 1/(1 - x - x^8 - x^15 + x^16).at n=51A173925
• Numbers that can be represented as a sum of two distinct nontrivial prime powers in three or more ways.at n=22A225104
• Numbers k that are the product of four distinct primes such that x^2+y^2 = k has integer solutions.at n=35A248712
• Coefficients in Molien series for 5-dimensional faithful representation of Horrocks-Mumford group G_{HM}.at n=39A258702
• Number of 3 X n integer arrays with each element equal to the number of horizontal and antidiagonal neighbors not equal to itself.at n=23A265993
• Reversion of x - x^2 - x^6.at n=10A276989
• Integers that are the sum of two consecutive semiprimes, as well as the product of two consecutive semiprimes.at n=8A288955
• a(n) = (n^2 + 1)*(n^2 + 2).at n=12A304579