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A293479
Composite numbers k = concat(MSD(k),x) such that the sum of the aliquot parts of k is equal to the sum of the aliquot parts of x.
0
1219, 1339, 3959, 4189, 7519, 11569, 11947, 27347, 35579, 37391, 38579, 45391, 46097, 77593, 81407, 94319, 94807, 95299, 96139, 97271, 99691, 102937, 106159, 107629, 115069, 131917, 137533, 158221, 168637, 201659, 223997, 339629, 345911, 352829, 362771, 363191
OFFSET
1,1
EXAMPLE
sigma(27347) - 27347 = 30240 - 27347 = 2893 and sigma(7347) - 7347 = 10240 - 7347 = 2893.
MAPLE
with(numtheory): P:=proc(q) local a, k, n, p, x, y; for n from 2 to q do
if not isprime(n) then x:=n mod 10^(ilog10(n));
if sigma(n)-n=sigma(x)-x then print(n); fi; fi; od; end: P(10^6);
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Paolo P. Lava, Oct 10 2017
STATUS
approved