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A272141 Numbers such that the concatenation of their aliquot parts, in ascending order, are prime numbers. 2
9, 14, 21, 26, 27, 34, 35, 46, 49, 55, 57, 58, 62, 74, 98, 115, 118, 143, 155, 158, 161, 166, 169, 178, 183, 187, 194, 201, 202, 209, 214, 215, 218, 219, 221, 226, 245, 265, 279, 287, 295, 298, 309, 314, 323, 326, 327, 329, 335, 341, 355, 371, 374, 377, 381 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..10000

EXAMPLE

Aliquot parts of 9 are 1, 3 and concat(1,3) = 13 is prime;

aliquot parts of 3127 are 1, 53, 59 and concat(1,53,59) = 15359 is prime.

MAPLE

with(numtheory): P:= proc(q) local a, b, k, n;

for n from 1 to q do a:=sort([op(divisors(n))]); b:=0;

for k from 1 to nops(a)-1 do b:=b*10^(ilog10(a[k])+1)+a[k]; od;

if isprime(b) then print(n); fi; od; end: P(10^9);

MATHEMATICA

Select[Range@ 384, PrimeQ@ FromDigits@ Flatten@ IntegerDigits@ Most@ Divisors@ # &] (* Michael De Vlieger, Apr 21 2016 *)

CROSSREFS

Cf. A176553, A272142.

Sequence in context: A272308 A186778 A070552 * A289548 A001198 A151915

Adjacent sequences:  A272138 A272139 A272140 * A272142 A272143 A272144

KEYWORD

nonn,base,easy

AUTHOR

Paolo P. Lava, Apr 21 2016

STATUS

approved

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Last modified July 24 02:56 EDT 2019. Contains 325290 sequences. (Running on oeis4.)