257049

Appears in sequences

• E.g.f.: exp(tanh(x)/cos(x)).at n=10A009274
• Squares that are a difference between 2 positive cubes.at n=12A038596
• a(n) = n^4 - 2*n^3 + 3*n^2 - 2*n + 1, the Alexander polynomial for reef and granny knots.at n=23A058031
• Solutions to mod(sigma(x), 6) = 5.at n=12A074384
• Squares sandwiched between two numbers divisible by squares.at n=32A088068
• Numbers of the form (3^i)*(13^j).at n=36A107364
• Numbers of the form (9^i)*(13^j), with i, j >= 0.at n=19A108748
• Squares for which both the sum of the digits and the product of the digits are cubes.at n=12A117687
• Squares which are anagrams of cubes.at n=21A161860
• Squares that become a prime number when prefixed with a 2.at n=21A167717
• Odd numbers N for which numerator(sigma(N)/N) is a prime.at n=19A193065
• Expansion of g.f. (1-4*x)/(1-13*x).at n=5A196663
• Number of (w,x,y,z) with all terms in {1,...,n} and w<2x and y<2z.at n=26A212503
• Squares which have one or more occurrences of exactly six different digits.at n=23A235721
• Integers m such that A240923(m) = 1, where A240923(n) = numerator(sigma(n)/n) - sigma(denominator(sigma(n)/n)).at n=17A240991
• Fixed points of A153212: After a(1) = 1, numbers of the form p_i1^i1 * p_i2^(i2-i1) * p_i3^(i3-i2) * ... * p_ik^(ik-i_{k-1}), where p_i's are distinct primes present in the prime factorization of n, with i1 < i2 < i3 < ... < ik, and k = A001221(n) and ik = A061395(n).at n=56A242421
• Squares representable as k*m + k + m, where k >= m > 1 are squares.at n=30A256074
• Magic sums of 3 X 3 semimagic squares of squares whose rows, columns, and at least one of the two main diagonals sum to the same number.at n=3A271021
• Numbers n such that n^3-1 is a sum of cubes in 1 way and a difference of cubes in 2 ways.at n=18A281789
• Number of n X 6 0..1 arrays with every element unequal to 0, 1 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.at n=13A299593