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.

A300005 Index of first occurrence of 2n in A300004 (or -1 of 2n does not occur), where A300004 are first differences of numbers not congruent to A000045(k) modulo A000045(k+1) for any k > 1.

This page as a plain text file.
%I A300005 #16 Mar 20 2018 11:34:45
%S A300005 1,0,5,26,14,100,323,1671,4293,10934,208741,753123,627460,87918559,
%T A300005 1137656208
%N A300005 Index of first occurrence of 2n in A300004 (or -1 of 2n does not occur), where A300004 are first differences of numbers not congruent to A000045(k) modulo A000045(k+1) for any k > 1.
%C A300005 It is only conjectured that every even number occurs in sequence A300004.
%C A300005 It would be interesting to know whether there are patterns or formulae for the indices at which the respective even numbers occur in.
%C A300005 As can be seen from a(2) = 0, sequence A300004 has been chosen to be 0-indexed, as for A292794.
%F A300005 a(n) = min { k | 2n = A300004(k) = A292794(k+1) - A292794(k) }.
%e A300005 Index n| gap 2n |   a(n)   | A292794(a(n))   with a(n) = the smallest k
%e A300005    1   |    2   |     1    |       4         such that  A300004(k) = 2n
%e A300005    2   |    4   |     0    |       0         = A292794(k+1) - A292794(k)
%e A300005    3   |    6   |     5    |      16
%e A300005    4   |    8   |    26    |     106
%e A300005    5   |   10   |    14    |      54
%e A300005    6   |   12   |    100   |     444
%e A300005    7   |   14   |    323   |     1456
%e A300005    8   |   16   |   1671   |     7614
%e A300005    9   |   18   |   4293   |    19602
%e A300005   10   |   20   |   10934  |    49966
%e A300005   11   |   22   |  208741  |    954384
%e A300005   12   |   24   |  753123  |   3443356
%e A300005   13   |   26   |  627460  |   2868820
%e A300005   14   |   28   | 87918559 |  401976096
%e A300005   15   |   30   |1137656208| 5201526136
%o A300005 (PARI) A300005=List();b=c=L=0;ng=2;for(n=1,oo, is_A292794(n)||next; c++; bittest(b,g=-L+L=n)&&next; b+=2^g; listput(A300005,[g,c-1,n-g]); g>ng&&next; listsort(A300005); for(i=ng/2,#A300005, A300005[i][1]>ng&&break; printf("%d,",A300005[i]);ng+=2))
%Y A300005 Cf. A300004, A292794, A000045.
%K A300005 nonn,more
%O A300005 1,3
%A A300005 _M. F. Hasler_, Mar 05 2018
%E A300005 a(14)-a(15) from _Jacques Tramu_, Feb 26 2018