51301

Appears in sequences

• Hyperperfect numbers: k = m*(sigma(k) - k - 1) + 1 for some m > 1.at n=14A007592
• Hyperperfect numbers: x such that x = 1 + k*(sigma(x)-x-1) for some k > 0.at n=18A034897
• Denominators of continued fraction convergents to sqrt(229).at n=8A041427
• Denominators of continued fraction convergents to sqrt(916).at n=12A042771
• a(n) = n^4 + 3*n^2 + 1.at n=15A057721
• Numbers generated by the Fibonacci polynomial x^4 + 3x^2 + 1.at n=14A085151
• First differences of Chebyshev polynomials S(n,227) = A098245(n) with Diophantine property.at n=2A098247
• Largest number that is not the sum of four (2n+1)-gonal numbers.at n=9A118368
• p^2-p-1 that is not prime, where p is prime.at n=29A119609
• Nonsemiprime hyperperfect numbers.at n=5A133447
• a(n) = 15*a(n-1) + a(n-2) with a(0) = 0, a(1) = 1.at n=5A154597
• a(n) = 61*n^2.at n=29A174333
• Number of strings of numbers x(i=1..6) in 0..n with sum i*x(i) equal to n*6.at n=14A184706
• Consider a number of k digits n = d_(k)*10^(k-1) + d_(k-1)*10^(k-2) + … + d_(2)*10 + d_(1). Sequence lists the numbers n such that Sum_{i=1..k-1}{phi(Sum_{j=1..i}{d_(j)*10^(j-1)})} = Sum_{i=1..k-1}{sigma(Sum_{j=1..i}{d_(k-j+1)*10^(i-j)})} (see example below).at n=21A244069
• Palindromic in bases 6 and 15.at n=24A249155
• a(n) = 2*n^3 + 3*n^2.at n=29A275709