A153227 Numbers k such that the string k is found at position 2k in the decimal digits of Pi.
5, 95, 171, 529, 1913, 2753, 60597, 831092, 9552919
Offset: 1
Examples
a(2) = 95 because 95 occurs at offset 190 (2*95) after the decimal in the digits of Pi.
Programs
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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[2*k:2*k+len(sk)]: print(k, end=", ") afind() # Michael S. Branicky, Jan 30 2022
Extensions
a(8) corrected by Paul Tek, Jun 09 2013
a(9) from Michael S. Branicky, Jan 30 2022