A153228 Numbers k such that the string k is found at position 3k in the decimal digits of Pi.

1, 2, 3, 85, 200, 447263

Offset: 1

Author

Gil Broussard, Dec 21 2008

Keywords

• base
• more
• nonn

Examples

			a(4) = 85 because 85 occurs at offset 255 (3*85) after the decimal in the digits of Pi.
		

Crossrefs

Cf. A057679, A057680, A109513, A109514, A153227.

Programs

Python

from sympy import S
# download https://stuff.mit.edu/afs/sipb/contrib/pi/pi-billion.txt, then
#with open('pi-billion.txt', 'r') as f: pi_digits = f.readline()
pi_digits = str(S.Pi.n(3*10**5+2))[:-2] # alternative to above
pi_digits = pi_digits.replace(".", "")
def afind():
    for k in range(1, len(pi_digits)):
        sk = str(k)
        if sk == pi_digits[3*k:3*k+len(sk)]:
            print(k, end=", ")
afind() # Michael S. Branicky, Jan 30 2022

Extensions

a(6) corrected by Michael S. Branicky, Jan 30 2022