A065991 Numbers k such that the first k base-4 digits of Pi expressed in decimal forms a prime.

1, 62, 3253, 4490, 62622

Offset: 1

Author

Robert G. Wilson v, Dec 10 2001

Keywords

• base
• nonn
• more

Comments

a(6) > 10^5. - Michael S. Branicky, Aug 14 2025

Examples

			The first 62 quaternary digits of Pi (A004603) are 30210033312222020201122030020310301030121202202320003130013031 = 16703571626015105435307505830654230989 in decimal, which is a prime.
		

Crossrefs

Cf. A004603, A060421.

Programs

Mathematica

Do[ If[ PrimeQ[ FromDigits[ First[ RealDigits[Pi, 4, n]], 4]], Print[n]], {n, 1, 4000} ]

Extensions

a(4) from Pontus von Brömssen, Aug 02 2025

a(5) from Michael S. Branicky, Aug 13 2025