cp's OEIS Frontend

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.

A380854 Integers m for which m = Sum (d_i + 1)^k, where m is k decimal digits long and d_i are the digits of m.

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%I A380854 #8 Feb 07 2025 13:10:53
%S A380854 141,251,560,664807556,424710875510,863812804425,
%T A380854 137134427278403350052,366828486147473227474,
%U A380854 186740753582576522645847734
%N A380854 Integers m for which m = Sum (d_i + 1)^k, where m is k decimal digits long and d_i are the digits of m.
%e A380854 664807556 is a term since it has 9 digits and (6+1)^9+(6+1)^9+(4+1)^9+(8+1)^9+(0+1)^9+(7+1)^9+(5+1)^9+(5+1)^9+(6+1)^9 = 664807556.
%o A380854 (Python)
%o A380854 from itertools import chain, combinations_with_replacement, count, islice
%o A380854 def A380854_gen(): # generator of terms
%o A380854     yield from chain.from_iterable(sorted(map(lambda s:sum((d+1)**l for d in s),sorted(filter(lambda s:tuple(sorted(map(int,str(m:=sum((d+1)**l for d in s)))))==s and 10**l>m>=10**(l-1),combinations_with_replacement(range(10),l))))) for l in count(1))
%o A380854 A380854_list = print(list(islice(A380854_gen(),8)))
%Y A380854 Cf. A005188, A261433, A380810.
%K A380854 nonn,more,base
%O A380854 1,1
%A A380854 _Chai Wah Wu_, Feb 06 2025
%E A380854 a(1)-a(3) from _Paolo P. Lava_
%E A380854 a(9) from _Chai Wah Wu_, Feb 07 2025