%I #10 Jan 30 2022 15:58:42
%S 1,2,3,85,200,447263
%N Numbers k such that the string k is found at position 3k in the decimal digits of Pi.
%e a(4) = 85 because 85 occurs at offset 255 (3*85) after the decimal in the digits of Pi.
%o (Python)
%o from sympy import S
%o # download https://stuff.mit.edu/afs/sipb/contrib/pi/pi-billion.txt, then
%o #with open('pi-billion.txt', 'r') as f: pi_digits = f.readline()
%o pi_digits = str(S.Pi.n(3*10**5+2))[:-2] # alternative to above
%o pi_digits = pi_digits.replace(".", "")
%o def afind():
%o for k in range(1, len(pi_digits)):
%o sk = str(k)
%o if sk == pi_digits[3*k:3*k+len(sk)]:
%o print(k, end=", ")
%o afind() # _Michael S. Branicky_, Jan 30 2022
%Y Cf. A057679, A057680, A109513, A109514, A153227.
%K base,more,nonn
%O 1,2
%A _Gil Broussard_, Dec 21 2008
%E a(6) corrected by _Michael S. Branicky_, Jan 30 2022