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A377473 Distinct first differences of Colombian or self numbers (A377472), listed in the order they appear.

%I A377473 #20 May 02 2025 01:34:33
%S A377473 2,11,15,28,41,54,67,80,93,106,119,101,118,131,144,157,170,183,196,
%T A377473 209,24,90,204,221,234,247,260,273,286,299,35,79,294,307,324,337,350,
%U A377473 363,376,389,46,68,384,397,410,427,440,453,466,479,57,474,487,500
%N A377473 Distinct first differences of Colombian or self numbers (A377472), listed in the order they appear.
%C A377473 See A377474 for the indices where these first differences appear for the first time.
%H A377473 Daniel Mondot, <a href="/A377473/b377473.txt">Table of n, a(n) for n = 1..10000</a>
%F A377473 a(n) = A377423(n) + 1.
%e A377473 A377472(n) = 2 = a(1) for all n <= 4. Then, A377472(n) = 11 = a(2) up to n = 13.
%e A377473 Then again, A377472(14..23) = (2, 11, ..., 11) and similarly up to n = 94.
%e A377473 But A377472(103) = 15 = a(3). Then the previous pattern repeats, with A377472(n) = 2 for n = 112, 122, ..., 192, followed by A377472(n) = 15 at n = 201, 299, 397, ..., 887.
%e A377473 Then A377472(984) = 28 = a(4), and it goes on with A377472(n) = 2 at n = 992, 1002, ..., 1072, and so on, with A377472(n) = 28 at n = 1962, 2940, 3918, ..., 8808.
%e A377473 Then A377472(9785) = 41 = a(5), and the whole previous pattern repeats, with A377472(9881) = 15, then A377472(10762) = 28 etc.
%e A377473 At n = 97786, we find A377472(n) = 54 = a(6), and again the whole previous pattern repeats again 8 more times, each time separated by a 54, until we have, at n = 977787, A377472(n) = 67 = a(7). And so on.
%o A377473 (PARI) A377473_upto(N=9, show=1)={my(o, c, d, L=List()); for(n=1+o=1, oo, is_A003052(n)||next; c++; if(!setsearch(L, d=n-o), show && printf("%d, ",[c,d]); listput(L,d); #L<N||break); o=n);L}
%Y A377473 Cf. A003052 (Colombian numbers), A377472 (1st differences of Colombian numbers), A163139 (= A377472 - 1), A377423.
%K A377473 nonn,base
%O A377473 1,1
%A A377473 _M. F. Hasler_, Oct 30 2024
%E A377473 Terms a(9) onward computed from A377423 by _Max Alekseyev_, Dec 31 2024