

A196788


a(n) is the first occurrence of n in A196697.


0



1, 1805, 133, 2, 3, 4, 5, 13, 6, 9, 8, 10, 19, 16, 32, 24, 74, 30, 18, 60, 168, 20, 42, 90, 180, 210, 186, 408, 144, 1020, 1050, 900, 2520, 3348, 2850, 5520, 3390, 774, 5760
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OFFSET

1,2


COMMENTS

a(39+k) > 9594, for any k >= 1. It is getting much harder for n>39. It took the Mathematica program weeks to get the first 39 items.


LINKS



EXAMPLE

...


MATHEMATICA

b = 2; max = 39; Array[fa, max]; Do[
fa[k] = 0, {k, 1, max}]; filled = 0; i = 0; While[filled < max, i++;
c1 = b^i; cs = {};
Do[c2 = b^j; cp = c1 + c2 + 1; If[PrimeQ[cp], cs = Union[cs, {cp}]];
cp = c1 + c2  1; If[PrimeQ[cp], cs = Union[cs, {cp}]];
cp = c1  c2 + 1; If[PrimeQ[cp], cs = Union[cs, {cp}]];
cp = c1  c2  1;
If[PrimeQ[cp], cs = Union[cs, {cp}]], {j, 0, i  1}];
ct = Length[cs];
If[ct <= max, If[fa[ct] == 0, fa[ct] = i; filled++]]]; Table[
fa[k], {k, 1, max}]


CROSSREFS



KEYWORD

nonn,more


AUTHOR



STATUS

approved



