Heptehectillion is equal to \(10^{3\cdot10^{321} + 3}\).[1] It is defined using Sbiis Saibian's generalization of Jonathan Bowers' -illion system.
Approximations[]
| Notation | Lower bound | Upper bound |
|---|---|---|
| Arrow notation | \(1000\uparrow(1+10\uparrow321)\) | |
| Down-arrow notation | \(1000\downarrow\downarrow108\) | \(143\downarrow\downarrow150\) |
| Steinhaus-Moser Notation | 147[3][3] | 148[3][3] |
| Copy notation | 2[2[322]] | 3[3[322]] |
| H* function | H(H(106)) | |
| Taro's multivariable Ackermann function | A(3,A(3,1066)) | A(3,A(3,1067)) |
| Pound-Star Notation | #*((1))*((3))*9 | #*((1))*((4))*9 |
| BEAF | {1000,1+{10,321}} | |
| Hyper-E notation | E(3+3E321) | |
| Bashicu matrix system | (0)(1)[32] | (0)(1)[33] |
| Hyperfactorial array notation | (175!)! | (176!)! |
| Fast-growing hierarchy | \(f_2(f_2(1059))\) | \(f_2(f_2(1060))\) |
| Hardy hierarchy | \(H_{\omega^22}(1059)\) | \(H_{\omega^22}(1060)\) |
| Slow-growing hierarchy | \(g_{\omega^{\omega^{\omega^23+\omega2+1}3+3}}(10)\) | |