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Digital sum (base the n-th prime) of n^4.
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%I #11 Sep 24 2016 04:28:15

%S 1,4,5,10,15,24,17,28,27,60,31,36,81,70,71,68,117,96,37,120,81,100,

%T 139,192,97,176,123,174,205,128,193,126,137,220,201,216,133,196,397,

%U 296,189,396,321,256,305,280,331,396,445,292,313,256,481,556,417,326,553,256

%N Digital sum (base the n-th prime) of n^4.

%H G. C. Greubel, <a href="/A135104/b135104.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = ds_prime(n)(n^4), where ds_prime(n) = digital sum base the n-th prime.

%F a(n) = n^4 - (prime(n)-1)*Sum{k>0} ( floor(n^4/prime(n)^k) ).

%e a(2) = ds_prime(2)(2^4) = ds_3(16) = 1+2+1 = 4;

%e a(6) = ds_prime(6)(6^4) = ds_13(1296) = 7+8+9 = 24.

%t Table[Total[IntegerDigits[n^4, Prime[n]]], {n, 50}] (* _G. C. Greubel_, Sep 23 2016 *)

%o (PARI) a(n) = vecsum(digits(n^4, prime(n))); \\ _Michel Marcus_, Sep 24 2016

%Y Cf. A000040, A007953, A054899, A075771, A131451, A133620, A133900, A134599.

%K nonn,base

%O 1,2

%A _Hieronymus Fischer_, Dec 24 2007