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A293477 Composite numbers k = concat(MSD(k),x) such that k' = x', where k' is the arithmetic derivative of k. 1
169, 1219, 1339, 1966, 3959, 7519, 11569, 17845, 35579, 37391, 38579, 77593, 94249, 94319, 95299, 96139, 97271, 97969, 99691, 106159, 107629, 115069, 137533, 150071, 168505, 188297, 247589, 339629, 345911, 352829, 362771, 363191, 365399, 370259, 381779, 382043 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..150

EXAMPLE

169' = 69' = 26, so 169 is a term.

3959' = 959' = 144, so 3959 is a term.

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)); a:=x*add(op(2, p)/op(1, p), p=ifactors(x)[2]);

if n*add(op(2, p)/op(1, p), p=ifactors(n)[2])=a then print(n); fi; fi; od; end: P(10^6);

CROSSREFS

Cf. A000030 (MSD), A003415 (arithmetic derivative).

Sequence in context: A250988 A289338 A256979 * A264304 A241538 A231974

Adjacent sequences:  A293474 A293475 A293476 * A293478 A293479 A293480

KEYWORD

nonn,base,easy

AUTHOR

Paolo P. Lava, Oct 10 2017

STATUS

approved

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Last modified January 22 07:39 EST 2020. Contains 331139 sequences. (Running on oeis4.)