18673

Appears in sequences

• Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite BEA = Beta Na7[Al7Si57O128] starting with a T6 atom.at n=13A019072
• Numbers k such that 255*2^k-1 is prime.at n=39A050886
• Numbers n such that sigma(n)=reversal(n)-n.at n=2A072394
• The a(n)-th highly-composite number (A002182) is the first one divisible by 2^n.at n=16A072847
• Composite numbers generated by the Euler polynomial x^2 + x + 41.at n=24A145292
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 1, -1), (0, 0, -1), (0, 1, 0), (1, 0, 1)}.at n=8A150161
• a(1) = 1; a(2) = 9; for n>2, a(n) = smallest number of the form 4k+1 and a(n) > a(n-1) such that the pairwise sums of elements are all semiprimes.at n=6A175532
• Number of different hook length multisets of partitions of n.at n=40A180652
• Number of n X 5 0..1 arrays with antidiagonals unimodal and rows and diagonals nondecreasing.at n=7A224035
• Number of ordered triples (i,j,k) with |i|, |j|, |k|, |i*j*k| <= n.at n=36A226359
• Semiprimes generated by the Euler polynomial x^2 + x + 41.at n=24A228183
• a(n) = (1/4)*n^4 - (1/2)*n^3 + (3/4)*n^2 - (1/2)*n + 41.at n=16A259552
• Where the ratio A235027(n)/n obtains record values.at n=14A290078
• A290865(n) -(n-1).at n=27A290876
• a(n) is the row of the Trithoff (tribonacci) array that contains the tails of the sequence which is n times the tribonacci numbers.at n=23A351685
• Numbers k such that k+i^2, i=0..6 are all semiprimes.at n=6A361262