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A175076 Composites c which end at 2 under iterations of {r mod (max prime p < r)} starting at r = c. 2
9, 15, 21, 25, 28, 33, 36, 39, 45, 49, 52, 55, 58, 63, 66, 69, 75, 78, 81, 85, 88, 91, 94, 96, 99, 105, 111, 115, 118, 120, 122, 126, 129, 133, 136, 141, 144, 146, 148, 153, 156, 159, 162, 165, 169, 172, 175, 178, 183, 186, 188, 190, 195, 201, 204, 206, 208, 213, 216 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A175072. Union of a(n) and A175075 is A175072.

LINKS

Table of n, a(n) for n=1..59.

EXAMPLE

Iteration procedure for a(2) = 15: 15 mod 13 = 2. Iteration procedure for a(5) = 28: 28 mod 23 = 5, 5 mod 3 = 2.

MATHEMATICA

ce2Q[n_]:=NestWhileList[Mod[#, NextPrime[#, -1]]&, n, #>0&][[-2]]==2; Select[ Range[ 300], CompositeQ[#]&&ce2Q[#]&] (* Harvey P. Dale, Feb 09 2015 *)

CROSSREFS

Sequence in context: A046446 A046350 A225438 * A046337 A046315 A046372

Adjacent sequences:  A175073 A175074 A175075 * A175077 A175078 A175079

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Jan 23 2010

EXTENSIONS

More terms from R. J. Mathar, Sep 25 2010

STATUS

approved

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Last modified September 26 20:36 EDT 2020. Contains 337374 sequences. (Running on oeis4.)