23309

Appears in sequences

• a(n) = n*(n^2 - 1)/2 - 1.at n=34A117560
• Numbers k such that 2*k+1, 3*k+2, 4*k+3 and 5*k+4 are primes.at n=23A138700
• Number of ways 1/n can be expressed as the sum of four distinct unit fractions: 1/n = 1/w + 1/x + 1/y + 1/z satisfying 0 < w < x < y < z.at n=20A241883
• Lexicographically earliest sequence of distinct nonnegative terms wherein every digit of a(n) is the absolute difference of two adjacent digits in a(n+1).at n=40A362335