50692

Appears in sequences

• a(0)=1; a(n) = sigma_1(n) + sigma_3(n).at n=37A092345
• Pentagonal numbers for which the sum of the digits is also a pentagonal number.at n=22A117709
• Pentagonal numbers for which both the sum of the digits and the product of the digits are pentagonal numbers.at n=12A117711
• 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, 1), (1, -1, 0)}.at n=10A148780
• Perimeter s/6 (divided by 6) of primitive Pythagorean triangles such that perimeters are Averages of twin prime pairs, q=p+1, a=q^2-p^2, c=q^2+p^2, b=2*p*q, s=a+b+c, s-+1 are primes.at n=23A155176
• a(n) = phi(Lucas(n)).at n=24A197218
• Numbers n such that sigma(phi(n)) = sigma(n) - phi(n).at n=7A230371
• a(n) = n*(n^2 - 3*n + 4).at n=38A242659
• Number of odd parts in the partitions of n into 9 parts.at n=47A309656
• Numbers k such that k, k^2-1 and k^2+1 are all fine, where a number m is fine if its prime factors are all less than m^(1/3).at n=9A345896
• a(n) = prime(1+n)*A024451(n-1) - A024451(n), where A024451(n) is the numerator of Sum_{i = 1..n} 1/prime(i).at n=6A376419