61080

Appears in sequences

• a(n) = Sum_{k=0..n} (k+1) * A026780(n, n-k).at n=11A027252
• Numbers k such that sigma(phi(k)) = phi(sigma(k)-k).at n=6A058653
• Number of (n+1)X(2+1) 0..3 arrays with 2X2 subblock sum of squares lexicographically nondecreasing rowwise and nonincreasing columnwise.at n=1A235519
• T(n,k) = Number of (n+1) X (k+1) 0..3 arrays with 2 X 2 subblock sum of squares lexicographically nondecreasing rowwise and nonincreasing columnwise.at n=4A235521
• Number of (2+1)X(n+1) 0..3 arrays with 2X2 subblock sum of squares lexicographically nondecreasing rowwise and nonincreasing columnwise.at n=1A235522
• Triangle read by rows: T(n,k) is the number of compositions of n having k distinct parts (n>=1, 1<=k<=floor((sqrt(1+8*n)-1)/2)).at n=58A235998
• Number of (n+2) X (4+2) 0..3 arrays with every 3 X 3 subblock row and column sum not equal to 0 3 5 6 or 7 and every 3 X 3 diagonal and antidiagonal sum equal to 0 3 5 6 or 7.at n=24A252250
• a(n) = A008412(n-1) + A008412(n-2) for n>1, a(0)=0, a(1)=1.at n=24A287324