101025

Appears in sequences

• a(n) = n^2*(2*n^2 - 1); also Sum_{k=0..n-1} (2k+1)^3.at n=15A002593
• Numbers whose base-10 representation has exactly 6 runs.at n=13A043642
• a(1) = 1; a(n) is the smallest triangular number > a(n-1) which differs from it at every digit.at n=37A068855
• Transform of n^3 by the Riordan array (1/(1-x^2), x).at n=29A105636
• Triangular numbers for which the sum of the digits is a square.at n=25A117404
• Triangular arithmetic on half-squares: b(n)*(b(n) - 1)/2 where b(n) = floor(n^2/2).at n=30A227970
• Triangular numbers that are the product of a square number and a prime number.at n=24A253653
• Coefficients of mock modular form H_1^(3).at n=14A256049
• a(n) = n^2*(2*n^2 + (-1)^n).at n=15A275496
• Numbers that have exactly 7 representations as a k-gonal number, P(n,k) = n*((k-2)*n - (k-4))/2, k and n >= 3.at n=18A321157
• Triangular numbers that are sum of squares of two distinct triangular numbers.at n=26A346386
• Triangular numbers whose sum of digits is 9.at n=20A375824
• Numbers k such that k-1 | sigma+(k) where sigma+ is A107758.at n=5A386390
• Numbers k for which gcd(k, A003961(k)) = gcd(sigma(k), A003961(k)) > 1, and that satisfy Euler's condition for odd perfect numbers (A228058).at n=2A387166