26754

Appears in sequences

• Aliquot sequence starting at 138.at n=19A008888
• Aliquot sequence starting at 150.at n=18A008889
• Aliquot sequence starting at 168.at n=16A008890
• Aliquot sequence starting at 570.at n=14A074907
• Triangle read by rows: T(n, m) = number of painted forests on labeled vertex set [n] with m trees. Also number of painted forests with exactly n - m edges.at n=22A106834
• a(n) = (5*n^3+12*n^2+n+6)/6.at n=31A114211
• Numbers k such that k^6 + 82991 is prime.at n=4A126893
• Numbers m such that the GCD of the x's that satisfy sigma(x) = m is 4.at n=29A241649
• Numbers n for which there exists k < n such that A000203(k) = A000203(n) and A007947(k) = A007947(n), where A000203 gives the sum of divisors, and A007947 gives the squarefree kernel of n.at n=3A255335
• The least number k > A255334(n) for which A000203(k) = A000203(A255334(n)) and A007947(k) = A007947(A255334(n)), where A000203 gives the sum of divisors, and A007947 gives the squarefree kernel of n.at n=3A255423
• Numbers k such that card({x|sigma(x)=k}) > 1 and (Sum_{sigma(x)=k} x) < k.at n=33A258931
• Sequence lists numbers k > 1 such that k^4 == phi(k) (mod sigma(k)), where phi = A000010 and sigma = A000203.at n=5A324216
• Sum of the areas of all r X s rectangles such that r + s = 2n, with r, s composite.at n=38A334229
• a(n) is the number of ways to split [n] = {1,2,...,n} into two (possibly empty) complementary intervals {1,2,...,i} and {i+1,i+2,...,n} and then, if both intervals are nonempty, select 2 nonempty blocks/cells (i.e., subintervals) from each of them, or if one of the intervals is empty, select 2 nonempty blocks/cells from the nonempty interval.at n=20A353232