%I #36 Jan 14 2023 10:50:19

%S 1,4,8,9,32,64,81,441,841,961,7744,7776,8874441,9853321,999887641

%N Perfect powers whose digits are in nonincreasing order and do not include 0.

%C a(16) > 10^45 if it exists. - _Michael S. Branicky_, Jun 19 2022

%o (Python)

%o from sympy import perfect_power as pp

%o from itertools import count, islice, combinations_with_replacement as mc

%o def agen():

%o yield 1

%o for d in count(1):

%o nd = (int("".join(m)) for m in mc("987654321", d))

%o yield from sorted(filter(pp, nd))

%o print(list(islice(agen(), 14))) # _Michael S. Branicky_, Jun 16 2022

%o (PARI) isok(m) = if (ispower(m), my(d=digits(m)); vecmin(d) && (d == vecsort(d,,4))); \\ _Michel Marcus_, Jun 17 2022

%Y Cf. A001597, A009996, A028822, A062826.

%K nonn,base,more

%O 1,2

%A _Jon E. Schoenfield_, Jun 16 2022