cp's OEIS Frontend

A372055 For a positive number k, let L(k) denote the list consisting of k followed by the prime factors of k, with repetition, in nondecreasing order; sequence gives k such that the digits of L(k) are in nondecreasing order.

%I A372055 #24 Mar 29 2025 19:45:40
%S A372055 1,2,3,5,7,11,12,25,35,111,112,125,222,245,333,335,445,1225,2225,
%T A372055 11125,33445,334445,3333335,3334445,3444445,33333445,333333335,
%U A372055 334444445,3333333335,33333334445,333333333335,33333333334445,33333333444445,444444444444445,2222222222222225
%N A372055 For a positive number k, let L(k) denote the list consisting of k followed by the prime factors of k, with repetition, in nondecreasing order; sequence gives k such that the digits of L(k) are in nondecreasing order.
%C A372055 This is the union of {1,2,3,5,7}, A004022, and A372029.
%e A372055 L(1) = [1], L(2) = [2,2], L(11) = [11,11], L(12) = [12,2,2,3].
%e A372055 See A372029 for further examples.
%e A372055 The prime k = 1111111111111111111 = A004022(2) will eventually be a term, since L(1111111111111111111) = [1111111111111111111,1111111111111111111], which certainly has digits in nondecreasing order.
%Y A372055 Cf. A004022, A372029.
%K A372055 nonn,base
%O A372055 1,2
%A A372055 _Scott R. Shannon_ and _N. J. A. Sloane_, Apr 22 2024
%E A372055 More terms from _Michael S. Branicky_, Apr 23 2024 using A004022 and A372029.