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A130007 Products of two reversible primes that are the reverse of each other such that the products are also the sum of three consecutive primes. 1
49, 121, 1207, 22801, 36481, 117907, 863041, 11986939, 32021347, 83148061, 88245211, 106110601, 217297081, 238733401, 242587711, 461772733, 487538353, 606191323, 683819293, 700500007, 758794243, 966634069, 989479087, 995821039, 1117186159, 1205213749, 1208515279 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..10000

EXAMPLE

121 = 11 * 11 = 37 + 41 +43

1207 = 17 * 71 = 397 + 401 + 409

117907 = 157 * 751 = 39293 + 39301 + 39313

MATHEMATICA

PrevPrim[n_] := Block[{k = n - 1}, While[ !PrimeQ[k], k-- ]; k]; NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; pal[n_] := FromDigits@ Reverse@ IntegerDigits@n; fQ[n_] := Block[{pn = pal@n, p, q, r, s}, q = PrevPrim[ Ceiling[n*pn/3]]; p = PrevPrim@q; r = NextPrim[ Floor[n*pn/3]]; s = NextPrim@r; n*pn == p + q + r || n*pn == q + r + s]; pd = 6; lst = {}; Do[ pd = NextPrim@pd; If[ PrimeQ@pd && fQ@pd, Print[pd*pal@pd]; AppendTo[lst, pd*pal@pd]], {n, 1000}]; lst = Union@lst - Robert G. Wilson v, Jun 19 2007

CROSSREFS

Cf. A007500.

Sequence in context: A115557 A167718 A080665 * A202331 A287005 A044300

Adjacent sequences:  A130004 A130005 A130006 * A130008 A130009 A130010

KEYWORD

base,nonn

AUTHOR

Paolo P. Lava and Giorgio Balzarotti, Jun 15 2007

EXTENSIONS

Corrected and extended by Robert G. Wilson v, Jun 19 2007

Corrected and extended and definition clarified by Chai Wah Wu, Feb 25 2018

STATUS

approved

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Last modified September 17 16:57 EDT 2019. Contains 327136 sequences. (Running on oeis4.)