package main import ( "bufio" "fmt" "math" "os" "sort" "strconv" ) var sc = bufio.NewScanner(os.Stdin) var wr = bufio.NewWriter(os.Stdout) func out(x ...interface{}) { fmt.Fprintln(wr, x...) } func getI() int { sc.Scan() i, e := strconv.Atoi(sc.Text()) if e != nil { panic(e) } return i } func getF() float64 { sc.Scan() i, e := strconv.ParseFloat(sc.Text(), 64) if e != nil { panic(e) } return i } func getInts(N int) []int { ret := make([]int, N) for i := 0; i < N; i++ { ret[i] = getI() } return ret } func getS() string { sc.Scan() return sc.Text() } // min, max, asub, absなど基本関数 func max(a, b int) int { if a > b { return a } return b } func min(a, b int) int { if a < b { return a } return b } // min for n entry func nmin(a ...int) int { ret := a[0] for _, e := range a { ret = min(ret, e) } return ret } // max for n entry func nmax(a ...int) int { ret := a[0] for _, e := range a { ret = max(ret, e) } return ret } func asub(a, b int) int { if a > b { return a - b } return b - a } func abs(a int) int { if a >= 0 { return a } return -a } func lowerBound(a []int, x int) int { idx := sort.Search(len(a), func(i int) bool { return a[i] >= x }) return idx } func upperBound(a []int, x int) int { idx := sort.Search(len(a), func(i int) bool { return a[i] > x }) return idx } const mod = int(1e9 + 7) func main() { defer wr.Flush() sc.Split(bufio.ScanWords) sc.Buffer([]byte{}, 1000000) // this template is new version. // use getI(), getS(), getInts(), getF() N := getI() A := getInts(N) dp := make([]int, N) dp[0] = 1 M := int(math.Sqrt(float64(N))) Sum := make([][]int, M+1) for i := 0; i < M+1; i++ { Sum[i] = make([]int, M+1) } for i := 0; i < N; i++ { if i > 0 && A[i-1] != 1 { dp[i] += dp[i-1] dp[i] %= mod } for j := 0; j < M+1; j++ { if j > 0 { dp[i] += Sum[j][i%j] dp[i] %= mod } } if A[i] <= M { Sum[A[i]][i%A[i]] += dp[i] Sum[A[i]][i%A[i]] %= mod } else { for j := 0; i < N; j++ { X := j*A[i] + A[i] + i if X >= N { break } dp[X] += dp[i] dp[X] %= mod } } } out(dp[N-1]) }