# [seqfan] A177949 two/three petty remarks

zak seidov zakseidov at yahoo.com
Sun May 16 04:29:13 CEST 2010

As to:
%N A177949 String of 41 consecutive numbers wich are not primes but relatively prime to the previous term (from 15685 to 15726).

two/three petty remarks:

1) this is not "string" but "sequence"

2) from 15685 to 15726 there are 42 consecutive numbers,
not 41

3)better to start with 15684 (and get 43 consecutive composite numbers, or prime gap = 44, see a(22) in
A000230 Smallest prime p such that there is a gap of 2n between p and next prime.

4) "consecutive numbers which (not "wich"!) are ...relatively prime to the previous term" -
this is OK but excessive:
any two consecutive numbers are co-prime.

5) Mmca code is too complex if not irrelevant at all.

6) sequence may be safely deleted  -
I admit that this one ain't "petty" remark ;-)

One of those Ass.Eds,
Zak

%%%%%%%%%%%%%%%%%%
%S A177949 15685,15686,15687,15688,15689,15690,15691,15692,
%N A177949 String of 41 consecutive numbers wich are not primes but relatively prime to the previous term (from 15685 to 15726).
%t A177949 rPrimeNext[n_]:=Module[{k},k=n+1;While[PrimeQ[k]||GCD[n,k]!=1,k++ ];k]; a=1;lst={a};Do[AppendTo[lst,a=rPrimeNext[a]],{n,0,2*7!}];lst1=lst; q=41;lst={};Do[If[lst1[[n+q]]-lst1[[n]]==q,AppendTo[lst,lst1[[n]]]],{n,0,Length[lst1]-q}];lst; a=FromDigits[lst];Table[n,{n,a,a+q}]

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