20425

Appears in sequences

• Pseudoprimes to base 7.at n=30A005938
• Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite RUT = RUB-10 R4[B4Si32O72] starting from a T3 atom.at n=13A019232
• Convolution of Lucas numbers and (1, p(1), p(2), ...).at n=15A023617
• Fifth-from-right diagonal of triangle A121207.at n=7A045500
• a(n) equals floor(Vc(n) - Vs(n)), where Vc(n) is the volume of the cube with side length n and Vs(n) is the volume of the sphere of diameter n.at n=34A057671
• Indices of the start of a string of 24 consecutive squares whose sum is a square.at n=19A094196
• Triangle read by rows: T(n,k) is the number of set partitions of {1,2,...,n} in which the size of the last block is k, 1<=k<=n; the blocks are ordered with increasing least elements.at n=58A124496
• Number of partitions of 2*n-1 into parts not greater than n.at n=18A171985
• Number A(n,k) of 3n-length k-ary words that can be built by repeatedly inserting triples of identical letters into the initially empty word; square array A(n,k), n>=0, k>=0, read by antidiagonals.at n=49A213028
• Number of 3 X n 0..1 arrays with rows nondecreasing and antidiagonals unimodal.at n=29A224134
• Pseudoprimes to base 7 that are not squarefree.at n=8A243089
• Euler pseudoprimes to base 7: composite integers such that abs(7^((n - 1)/2)) == 1 mod n.at n=21A262054
• Third diagonal sequence of the Sheffer triangle A094816 (special Charlier).at n=18A290312
• Total number of divisors d of m (counted with multiplicity), such that the prime signature of d is a partition of two and m runs through the set of least numbers whose prime signature is a partition of n.at n=18A309691
• Number of integer partitions whose sum of primes of parts equals their sum of parts plus n.at n=39A331387
• Triangle read by rows: T(n,m) (n >= m >= 1) = number of vertices formed by drawing the lines connecting any two of the 2*(m+n) perimeter points of an m X n grid of squares.at n=42A331453
• a(n) is the number of vertices formed by n-secting the angles of an octagon.at n=39A335770
• Number of integer partitions of n whose greatest part is at most one more than the sum of the other parts.at n=37A336106
• 31-gonal numbers: a(n) = n*(29*n-27)/2.at n=38A360488
• Sum over all partitions of n of the number of elements with minimal multiplicity in their partition.at n=32A372632