18654

Appears in sequences

• Sum(j=1,n,floor(A000041(j)/j)).at n=46A086736
• Numbers k such that k and 5*k, taken together, are pandigital.at n=11A115925
• Triangle read by rows: counts permutations by number of big descents.at n=33A120434
• Triangle, read by rows, where row n lists the coefficients of x^k, k=1..2^n, in the n-th iteration of (x + x^2) for n>=0.at n=40A122888
• Numbers k such that k*(k+1)-1 and k*(k+1)+1 are twin primes and k*(k+3)-1 and k*(k+3)+1 are also twin primes.at n=16A138303
• Number of binary strings of length n with equal numbers of 00000 and 01110 substrings.at n=15A164187
• a(n) = largest number k such that k and k * n taken together have distinct digits, or 0 if no such k exists.at n=4A173780
• Triangle T(n,k), read by rows, given by (0,1,0,2,0,3,0,4,0,5,0,6,0,7,0,8,0,9,...) DELTA (2,0,3,0,4,0,5,0,6,0,7,0,8,0,9,...), where DELTA is the operator defined in A084938.at n=39A199335
• Triangle (read by rows) of coefficients of the polynomials (in ascending order) of the denominators of the generalized sequence of fractions f(n) defined recursively by f(1) = m/1; f(n+1) is chosen so that the sum and the product of the first n terms of the sequence are equal.at n=59A225200
• a(n) is the number of terms in the expansion of (x-y)*(x^4-y^4)*(x^9-y^9)*...*(x^(n^2)-y^(n^2)).at n=37A225549
• Expansion of Product_{k>=1} ((1 + x^(k^2)) / (1 - x^(k^2)))^k.at n=42A291667
• Numbers with arithmetic derivative which is a palindromic prime number (A002385).at n=28A359332