A373009 Decimal expansion of PentInv(1 + PentInv(2 + PentInv(3 + PentInv(4 + ... )))) where PentInv(n) = (1 + sqrt(1 + 24*n))/6.

1, 5, 4, 7, 1, 5, 7, 5, 8, 7, 2, 9, 7, 8, 7, 6, 6, 6, 1, 2, 5, 8, 8, 0, 7, 9, 4, 0, 0, 8, 6, 5, 1, 8, 4, 8, 3, 6, 2, 0, 6, 4, 1, 3, 1, 3, 4, 6, 8, 5, 0, 5, 1, 3, 4, 9, 8, 1, 6, 5, 8, 8, 4, 7, 3, 3, 8, 7, 5, 9, 7, 9, 8, 0, 1, 1, 1, 2, 3, 0, 3, 5, 2, 6, 4, 5, 7, 3, 6, 5, 5, 3, 1, 5, 8, 0, 7, 3, 4, 9, 4, 2, 9, 6, 0, 1, 6, 4, 7, 7, 7

Offset: 1

Author

Kelvin Voskuijl, May 22 2024

Keywords

• nonn
• cons

Comments

The inverse of the pentagonal numbers is defined here as (1 + sqrt(1 + 24*n))/6.

Examples

			1.54715758729787666125880794008651848362064131346850513...
		

Crossrefs

Cf. A365747 (triangular inverse), A072449 (square root), A099874 (cubes).

Cf. A000326 (pentagonal numbers).