login
This site is supported by donations to The OEIS Foundation.

 

Logo

The OEIS is looking to hire part-time people to help edit core sequences, upload scanned documents, process citations, fix broken links, etc. - Neil Sloane, njasloane@gmail.com

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A174214 a(n) = a(n-1)+1, if the previous term a(n-1) and n-1-(-1)^n are coprime, else a(n)=2*n-4. 5
14, 16, 17, 18, 19, 20, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 52, 53, 54, 55, 60, 62, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134 (list; graph; refs; listen; history; text; internal format)
OFFSET

9,1

LINKS

Table of n, a(n) for n=9..74.

V. Shevelev, Theorems on twin primes-dual case, arXiv:0912.4006 [math.GM], 2009-2014.

MAPLE

A174214 := proc(n) option remember ; if n = 9 then 14 ; elif gcd(procname(n-1), n-1-(-1)^n) = 1 then procname(n-1)+1 ; else 2*n-4 ; end if; end proc:

seq(A174214(n), n=9..100) ; # R. J. Mathar, Mar 16 2010

MATHEMATICA

a[n_] := a[n] = Which[n==9, 14, CoprimeQ[a[n-1], n-1-(-1)^n], a[n-1]+1, True, 2n-4]; Table[a[n], {n, 9, 100}] (* Jean-Fran├žois Alcover, Feb 02 2016 *)

CROSSREFS

Cf. A166945, A167495.

Sequence in context: A225758 A043663 A043703 * A072709 A241178 A158282

Adjacent sequences:  A174211 A174212 A174213 * A174215 A174216 A174217

KEYWORD

nonn,easy

AUTHOR

Vladimir Shevelev, Mar 12 2010

EXTENSIONS

a(15) corrected and sequence extended by R. J. Mathar, Mar 16 2010

a(15) corrected and a(35)-a(74) added by John W. Layman, Mar 16 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified May 28 16:24 EDT 2017. Contains 287241 sequences.