A053748 Positions of 4's in the decimal expansion of Pi.

3, 20, 24, 37, 58, 60, 61, 71, 88, 93, 105, 120, 126, 127, 146, 152, 158, 163, 183, 184, 189, 193, 202, 203, 218, 219, 224, 228, 252, 255, 263, 267, 272, 274, 279, 294, 297, 304, 322, 340, 349, 372, 377, 385, 387

Offset: 1

Author

Simon Plouffe, Feb 20 2000

Keywords

• nonn
• base

Examples

			Pi starts off 3.141592653589793238462643383279502884197..., with 4s in the hundredths' (10^(-2)s') place, which is the third digit counting the 3 in the ones' place. Then there's another 4 at the 10^(-19)s' place, which is the twentieth digit counting the initial 3. [_Alonso del Arte_, Oct 07 2013]
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000
• Index entries for sequences related to the number Pi

Crossrefs

Cf. A000796, A037003.

Programs

Mathematica

Flatten[Position[RealDigits[Pi, 10, 1000][[1]], 4]] (* Vincenzo Librandi, Oct 07 2013 *)

Formula

a(n) = A037003(n) + 1. - Georg Fischer, May 31 2021