

A205705


Numbers k for which 8 divides prime(k)prime(j) for some j<k; each k occurs once for each such j.


8



5, 6, 8, 8, 9, 10, 10, 11, 11, 12, 12, 12, 13, 14, 14, 14, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 18, 19, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 22, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23, 24, 24, 24, 25, 25, 25, 25, 26, 26, 26, 26, 26, 26
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OFFSET

1,1


COMMENTS

For a guide to related sequences, see A205558.


LINKS



EXAMPLE

The first six terms match these differences:
p(5)p(2)=113=8=8*1
p(6)p(3)=135=8=8*1
p(8)p(2)=193=16=8*2
p(8)p(5)=1911=8=8*1
p(9)p(4)=237=16=8*2
p(10)p(3)=295=24=8*3


MATHEMATICA

s[n_] := s[n] = Prime[n]; z1 = 900; z2 = 70;
f[n_] := f[n] = Floor[(1 + Sqrt[8 n  7])/2];
Table[s[n], {n, 1, 30}] (* A000040 *)
u[m_] := u[m] = Flatten[Table[s[k]  s[j], {k, 2, z1}, {j, 1, k  1}]][[m]]
Table[u[m], {m, 1, z1}] (* A204890 *)
v[n_, h_] := v[n, h] = If[IntegerQ[u[h]/n], h, 0]
w[n_] := w[n] = Table[v[n, h], {h, 1, z1}]
d[n_] := d[n] = Delete[w[n], Position[w[n], 0]]
k[n_] := k[n] = Floor[(3 + Sqrt[8 t[[n]]  1])/2]
j[n_] := j[n] = t[[n]]  f[t][[n]] (f[t[[n]]] + 1)/2
Table[k[n], {n, 1, z2}] (* A205705 *)
Table[j[n], {n, 1, z2}] (* A205706 *)
Table[s[k[n]], {n, 1, z2}] (* A205707 *)
Table[s[j[n]], {n, 1, z2}] (* A205708 *)
Table[s[k[n]]  s[j[n]], {n, 1, z2}] (* A205709 *)
Table[(s[k[n]]  s[j[n]])/c, {n, 1, z2}] (* A205710 *)


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



