A054303 Positions of 7's in the decimal expansion of sqrt(2).

12, 26, 36, 42, 45, 48, 54, 57, 60, 62, 64, 68, 72, 79, 88, 94, 99, 101, 118, 134, 136, 148, 169, 176, 179, 191, 198, 201, 210, 216, 219, 233, 238, 269, 281, 289, 298, 304, 344, 347, 352, 353, 359, 366, 373, 379, 387, 400, 411, 430, 431, 442, 465, 479, 496

Offset

1,1

Links

G. C. Greubel, Table of n, a(n) for n = 1..10000

Mathematica

Flatten[Position[RealDigits[Sqrt[2], 10, 500][[1]], 7]] (* G. C. Greubel, Jul 23 2019 *)

Prog

(Python)
from sympy import N, sqrt
def aupton(terms, precision=10000):
    idx, alst = -1, []
    root2_digits = str(N(sqrt(2), precision+2)).replace(".", "")[:-2]
    for i in range(terms):
        idx = root2_digits.find("7", idx+1)
        if idx != -1: alst.append(idx+1)
        else: print("Increase precision: got to", i); break
    return alst
print(aupton(55)) # Michael S. Branicky, Dec 26 2021

Crossrefs

Cf. A002193.

Cf. A054296, A054297, A054298, A054299, A054300, A054301, A054302 (0..6).

Cf. A054304, A054305 (8..9).

Sequence in context: A041286 A025138 A075689 * A184826 A119412 A105814

Adjacent sequences: A054300 A054301 A054302 * A054304 A054305 A054306

Keyword

nonn,base

Author

Simon Plouffe, Feb 20 2000

Status

approved