This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A355063 #40 Jul 01 2025 16:56:15
%S A355063 1,4,8,9,32,64,81,441,841,961,7744,7776,8874441,9853321,999887641
%N A355063 Perfect powers whose digits are in nonincreasing order and do not include 0.
%C A355063 a(16) > 10^45 if it exists. - _Michael S. Branicky_, Jun 19 2022
%t A355063 perfectPowerQ[n_] := n==1||GCD @@ FactorInteger[n][[All, 2]] > 1; (* A001597 *) Select[Range[10^5], perfectPowerQ[#] && Max[Differences[d=IntegerDigits[#]]]<1 && Count[d,0]==0&] (* _Stefano Spezia_, Jul 01 2025 *)
%o A355063 (Python)
%o A355063 from sympy import perfect_power as pp
%o A355063 from itertools import count, islice, combinations_with_replacement as mc
%o A355063 def agen():
%o A355063 yield 1
%o A355063 for d in count(1):
%o A355063 nd = (int("".join(m)) for m in mc("987654321", d))
%o A355063 yield from sorted(filter(pp, nd))
%o A355063 print(list(islice(agen(), 14))) # _Michael S. Branicky_, Jun 16 2022
%o A355063 (PARI) isok(m) = if (ispower(m), my(d=digits(m)); vecmin(d) && (d == vecsort(d,,4))); \\ _Michel Marcus_, Jun 17 2022
%Y A355063 Cf. A001597, A009996, A028822, A062826.
%K A355063 nonn,base,more
%O A355063 1,2
%A A355063 _Jon E. Schoenfield_, Jun 16 2022