editing

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Harvey P. Dale, <a href="/A136355/b136355.txt">Table of n, a(n) for n = 1..332</a>

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editing

editing

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Select[FoldList[Times, Prime[Range[2, 21]]], CompositeQ[#+2]&] (* Harvey P. Dale, Jun 08 2022 *)

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editing

_Enoch Haga (Enokh(AT)comcast.net), _, Dec 25 2007

Contribution from _Farideh Firoozbakht (mymontain(AT)yahoo.com), _, Aug 12 2009: (Start)

Edited with more terms by _Farideh Firoozbakht (mymontain(AT)yahoo.com), _, Aug 12 2009

Odd Numbers of the form P = product of the first k odd primes where P+2 is composite N with k consecutive prime factors not followed by prime N+2.

1155, 255255, 4849845, 111546435, 152125131763605, 6541380665835015, 16294579238595022365, 58644190679703485491635, 3929160775540133527939545, 278970415063349480483707695, 20364840299624512075310661735

This sequence is different from A070826 and/or A118750

Compute the product of k consecutive sequences of prime factors 3,5,7,11, etc. where k=1,2,3,4,5, etc. When odd composite N is not followed by prime N+2 add N to the sequence.

Contribution from Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 12 2009: (Start)

v=Select[Range[20], !PrimeQ[Product[Prime[k+1], {k, #}]+2]&]; Table[Product[Prime

[k+1], {k, v[[t]]}], {t, Length[v]}] (End)

easy,more,nonn,uned,new

easy,nonn

Edited with more terms by Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 12 2009

Compute the product of k consecutive sequences of prime factors 3,5,7,11, etc. where k=1,2,3,4,5, etc. Where When odd composite N is not followed by prime N+2 add N to the sequence.

easy,more,nonn,uned,new

Odd composite N with k consecutive prime factors not followed by prime N+2.

1155, 255255, 4849845, 111546435

1,1

This sequence is different from A070826 and/or A118750

Compute the product of k consecutive sequences of prime factors 3,5,7,11,etc. where k=1,2,3,4,5,etc. Where odd composite N is not followed by prime N+2 add N to the sequence.

a(1)=1155 because 1157 is not prime.

Cf. A136349-A136354 A136356-A136358 A070826 A118750.

easy,more,nonn,uned

Enoch Haga (Enokh(AT)comcast.net), Dec 25 2007

approved