import std.conv, std.functional, std.range, std.stdio, std.string; import std.algorithm, std.array, std.bigint, std.complex, std.container, std.math, std.numeric, std.regex, std.typecons; import core.bitop; class EOFException : Throwable { this() { super("EOF"); } } string[] tokens; string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; } int readInt() { return readToken.to!int; } long readLong() { return readToken.to!long; } real readReal() { return readToken.to!real; } bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } } bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } } int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; } int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); } int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); } void main() { debug { foreach (n; 1 .. 11) { int mn = n * n * n; auto perm = iota(n).array; do { int sum; foreach (i; 0 .. n) { sum += (perm[i] + 1) * (perm[(i + 1) % n] + 1); } chmin(mn, sum); } while (perm.nextPermutation); write(mn, ", "); } writeln; } try { for (; ; ) { const N = readLong(); // https://oeis.org/A110611 long ans; if (N == 1) { ans = 1; } else if (N % 2 == 0) { ans = (N^^3+3*N^^2+5*N-6)/6; } else { ans = (N^3+3*N^2+5*N-3)/6; } writeln(ans); } } catch (EOFException e) { } }