A153221 Numbers k such that the string k is found at position k-3 in the decimal digits of Pi.
51, 875, 62843, 242424, 4308765, 9710721, 24747689, 126987778
Offset: 1
Examples
a(1) = 51 because 51 occurs at offset (51-3) 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 ispal(s): return s == s[::-1] def afind(): for k in range(len(pi_digits)): sk = str(k) if sk == pi_digits[k-3:k-3+len(sk)]: print(k, end=", ") afind() # Michael S. Branicky, Jan 30 2022
Extensions
a(5)-a(8) from Michael S. Branicky, Jan 30 2022