288420

Appears in sequences

• Triangular numbers with only even digits.at n=21A117978
• Triangular numbers that are sandwiched between two semiprimes; or triangular numbers t such that t-1 and t+1 are both semiprime.at n=29A121898
• a(n) = 12167n - 3588.at n=23A156846
• Expansion of 1/((1-x)^2*(1-x^2)^3*(1-x^3)^2*(1-x^4)).at n=37A210068
• G.f. for Ehrhart quasi-polynomials for hyperplane arrangements of type E_7.at n=55A210633
• Triangular numbers that are the product of three distinct triangular numbers greater than 1.at n=29A225440
• Triangular arithmetic on half-squares: b(n)*(b(n) - 1)/2 where b(n) = floor(n^2/2).at n=39A227970
• Numbers k such that k^2 +- k +- 1 is prime for all four possibilities.at n=30A236056
• Expansion of g.f. A(x) satisfying 2 = Sum_{n=-oo..+oo} (-1)^n * x^(2*n) * (2*A(x) + x^(n-2))^(n+1).at n=11A363107
• Number of unordered pairs of distinct strict integer partitions of n.at n=37A366132
• Triangular numbers that are sandwiched between two squarefree semiprimes.at n=27A375384