cp's OEIS Frontend

A263079 Numbers n for which there does not exist any x > n such that A155043(x) < A155043(n).

%I A263079 #19 Feb 04 2025 21:24:55
%S A263079 1,2,3,4,6,8,9,10,12,14,18,20,22,24,25,26,28,30,32,34,38,40,42,44,46,
%T A263079 48,49,50,52,54,56,60,72,84,96,104,108,120,128,132,136,140,142,144,
%U A263079 150,152,156,160,162,168,170,180,182,184,186,188,190,192,194,198,200,204,208,210,216,220,225,228,240,248,252,260,264,276,280,288,296,300,308,312,320,328,340,352,360
%N A263079 Numbers n for which there does not exist any x > n such that A155043(x) < A155043(n).
%C A263079 Numbers n for which A263077(n) < n.
%C A263079 Numbers n for which A263078(n) is negative.
%C A263079 Numbers n at which point A155043(n) is the greatest lower bound for the rest of its terms from A155043(n) onward.
%H A263079 Antti Karttunen, <a href="/A263079/b263079.txt">Table of n, a(n) for n = 1..9165</a>
%e A263079 1 is present because A049820(1) = 0, thus A155043(1) = 1, while all the larger numbers require at least the same number of steps to reach zero.
%t A263079 a[0] = 0; a[n_] := a[n] = 1 + a[n - DivisorSigma[0, n]]; Position[Table[k = 3 n; While[a@ k >= a@ n, k--]; k - n, {n, 200}], _Integer?Negative] // Flatten (* _Michael De Vlieger_, Oct 13 2015 *)
%o A263079 (PARI)
%o A263079 n=0; i=0; while(n < 124340, n++; if((A263077(n) < n), i++; write("b263079.txt",i," ",n)));
%o A263079 \\ Other code as in A263077.
%o A263079 (Scheme)
%o A263079 ;; With _Antti Karttunen_'s IntSeq-library.
%o A263079 (define A263079 (MATCHING-POS 1 1 (COMPOSE negative? A263078)))
%Y A263079 Cf. A155043, A261089, A262503, A263077, A263078.
%Y A263079 Complement: A263080.
%K A263079 nonn
%O A263079 1,2
%A A263079 _Antti Karttunen_, Oct 09 2015