A272142 Numbers such that the concatenation of their aliquot parts, in descending order, are prime numbers.

8, 9, 10, 26, 34, 35, 49, 55, 56, 57, 62, 63, 75, 76, 77, 94, 95, 115, 122, 125, 142, 144, 146, 161, 169, 183, 194, 196, 203, 206, 219, 226, 235, 238, 254, 262, 265, 274, 275, 278, 290, 299, 302, 304, 305, 309, 320, 322, 332, 336, 338, 346, 355, 358, 361, 362

Offset

1,1

Links

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

Example

Aliquot parts of 8 are 1, 2, 4 and concat(4,2,1) = 421 is prime;
aliquot parts of 1822 are 1, 2, 911 and concat(911,2,1) = 91121 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 nops(a)-1 by -1 to 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@ 362, PrimeQ@ FromDigits@ Flatten@ IntegerDigits@ Reverse@ Most@ Divisors@ # &] (* Michael De Vlieger, Apr 21 2016 *)

Crossrefs

Cf. A176553, A272141.

Sequence in context: A283628 A343860 A308809 * A270039 A048020 A363760

Adjacent sequences: A272139 A272140 A272141 * A272143 A272144 A272145

Keyword

nonn,base,easy

Author

Paolo P. Lava, Apr 21 2016

Status

approved