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A109133 Numbers n such that (sum of digits)*(number of digits) + 1 is prime. 0
1, 2, 4, 6, 10, 11, 12, 14, 15, 17, 18, 20, 21, 23, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 41, 42, 44, 45, 47, 50, 51, 53, 54, 56, 59, 60, 62, 63, 65, 68, 69, 71, 72, 74, 77, 78, 80, 81, 83, 86, 87, 90, 92, 95, 96, 99, 101, 103, 105, 109, 110, 112, 114, 118, 121, 123, 127 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..67.

EXAMPLE

1234 is a term because 4*(1+2+3+4)+1 = 41.

MATHEMATICA

Select[Range[130], PrimeQ[Total[IntegerDigits[#]]IntegerLength[ #]+ 1]&] (* Harvey P. Dale, Jul 12 2011 *)

CROSSREFS

Cf. A110805.

Sequence in context: A089227 A204660 A275956 * A056077 A249428 A129630

Adjacent sequences:  A109130 A109131 A109132 * A109134 A109135 A109136

KEYWORD

base,easy,nonn

AUTHOR

Jason Earls, Aug 17 2005

STATUS

approved

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Last modified May 28 10:49 EDT 2020. Contains 334681 sequences. (Running on oeis4.)