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%I #7 Nov 19 2021 10:10:38
%S 11,19,61,68,101,109,110,116,118,161,166,169,181,188,190,199,601,608,
%T 610,616,619,661,680,1006,1010,1018,1019,1061,1066,1081,1090,1091,
%U 1096,1100,1106,1108,1109,1118,1160,1169,1180,1181,1186,1601,1606,1609,1610,1618
%N Numbers that are primes when turned upside down.
%D P. Giannopoulos, The Brainteasers (unpublished)
%H Michael S. Branicky, <a href="/A080789/b080789.txt">Table of n, a(n) for n = 1..10000</a>
%o (Python)
%o from sympy import isprime
%o from itertools import product
%o def ud(s):
%o return s[::-1].translate({ord('6'):ord('9'), ord('9'):ord('6')})
%o def auptod(maxdigits):
%o alst = []
%o for d in range(1, maxdigits+1):
%o for start in "16":
%o for p in product("01689", repeat=d-1):
%o s = start + "".join(p)
%o t, udt = int(s), int(ud(s))
%o if isprime(udt): alst.append(t)
%o return alst
%o print(auptod(4)) # _Michael S. Branicky_, Nov 19 2021
%Y Cf. A057770, A054047, A080788.
%K base,easy,nonn
%O 1,1
%A P. Giannopoulos (pgiannop1(AT)yahoo.com), Mar 12 2003
%E 610 inserted and a(24) and beyond from _Michael S. Branicky_, Nov 19 2021
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