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A157678 Numbers k such that k + floor(average of digits of k) is prime. 1
1, 12, 16, 27, 30, 34, 38, 41, 56, 63, 67, 70, 74, 89, 92, 96, 101, 102, 105, 107, 112, 125, 128, 130, 136, 146, 147, 154, 161, 164, 168, 175, 186, 188, 190, 193, 208, 210, 219, 226, 229, 231, 236, 237, 247, 254, 258, 265, 273, 276, 278, 280, 290, 305, 308, 309 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

EXAMPLE

n = 89 -> 89 + floor((8+9)/2) = 89 + 8 = 97 (prime).

n = 190 -> 190 + floor((1+9+0)/3) = 190 + 3 = 193 (prime).

MAPLE

a := proc (n) local nn: nn := convert(n, base, 10): if isprime(n+floor(add(nn[j], j = 1 .. nops(nn))/nops(nn))) = true then n else end if end proc: seq(a(n), n = 1 .. 350); # Emeric Deutsch, Mar 07 2009

PROG

(PARI) is(n)=isprime(sumdigits(n)\#digits(n)+n) \\ Charles R Greathouse IV, Dec 27 2013

CROSSREFS

Cf. A172367.

Sequence in context: A077617 A182074 A192609 * A334560 A109240 A020740

Adjacent sequences:  A157675 A157676 A157677 * A157679 A157680 A157681

KEYWORD

nonn,base

AUTHOR

Kyle D. Balliet, Mar 04 2009

EXTENSIONS

Corrected and extended by Emeric Deutsch, Mar 07 2009

STATUS

approved

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Last modified May 27 16:48 EDT 2022. Contains 354110 sequences. (Running on oeis4.)