20508

Appears in sequences

• Irregular square reversible numbers. Numbers which when squared and written backwards give a square again, but don't satisfy reverse(n^2) = reverse(n)^2.at n=19A129914
• Triangle of coefficients of polynomials u(n,x) jointly generated with A208762; see the Formula section.at n=51A208761
• Triangle T(n, k) = Numbers of ways to place k points on a triangular grid of side n so that no three of them are vertices of an equilateral triangle with sides parallel to the grid. Triangle read by rows.at n=34A243211
• Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 169", based on the 5-celled von Neumann neighborhood.at n=17A279547
• Integers k such that k^2 is not a palindrome and the square root of the reverse of k^2 yields an integer with the same number of digits as k that is not the reverse of k.at n=4A284986