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A284813 Numbers n such that n' = d_1^k + d_2^(k-2) + ... + d_k^1 where d_1, d_2,  ..., d_k are the digits of n, with MSD(n) = d_1 and LSD(n) = d_k, and n' is the arithmetic derivative of n. 0

%I

%S 4,766,2587,12629,104977,1068623,1844423,2056849,2089207,3126943,

%T 3216923,3410107,11894353,14467237,20409227,20544577,23417957,

%U 53531447,57145091

%N Numbers n such that n' = d_1^k + d_2^(k-2) + ... + d_k^1 where d_1, d_2, ..., d_k are the digits of n, with MSD(n) = d_1 and LSD(n) = d_k, and n' is the arithmetic derivative of n.

%e 766' = 385 = 7^3 + 6^2 + 6^1.

%p with(numtheory): P:=proc(q) local a,k,n,p; for n from 1 to q do a:=convert(n,base,10);

%p if add(a[k]^k,k=1..nops(a))=n*add(op(2,p)/op(1,p),p=ifactors(n)[2])

%p then print(n); fi; od; end: P(10^9);

%Y Cf. A003415, A284812

%K nonn,base,more

%O 1,1

%A _Paolo P. Lava_, Apr 07 2017

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Last modified June 18 18:09 EDT 2021. Contains 345120 sequences. (Running on oeis4.)