121800

Appears in sequences

• a(n) = n*(n+1)*(n+2)^2/6.at n=28A004320
• a(n) = binomial(n+2,2)*binomial(n+6,2).at n=23A104473
• Amicable triples: numbers such that sigma(x) = sigma(y) = sigma(z) = x+y+z, x<y<z. We order these triples according to the common value of sigma. Sequence gives x numbers.at n=27A125490
• a(n) = ((7 + sqrt(3))^n - (7 - sqrt(3))^n)/(2*sqrt(3)).at n=5A153598
• Triangle read by rows, k!*2^k*S_2(n, k) where S_m(n, k) are the Stirling-Frobenius subset numbers of order m; n >= 0, k >= 0.at n=32A225476
• Number of (n+2)X(4+2) 0..1 arrays with each 3X3 subblock having clockwise perimeter pattern 00000001 00000101 or 00010101.at n=6A260102
• Number of (n+2)X(7+2) 0..1 arrays with each 3X3 subblock having clockwise perimeter pattern 00000001 00000101 or 00010101.at n=3A260105
• Numbers of the form (p+1)*(p+3) where (p,p+2) is a twin prime pair (cf. A001359).at n=20A362941
• Numbers k such that binomial(k^2,k) == 0 (mod k^3).at n=18A371474
• Positive integers of the form k^2 - 1 that are the product of two other distinct positive integers of the form k^2 - 1.at n=23A372497