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A071422 a(n) = a(n-1) + sum of decimal digits of sigma(n), the sum of divisors of n. 1

%I

%S 1,4,8,15,21,24,32,38,42,51,54,64,69,75,81,85,94,106,108,114,119,128,

%T 134,140,144,150,154,165,168,177,182,191,203,212,224,234,245,251,262,

%U 271,277,292,300,312,327,336,348,355,367,379,388,405,414,417,426,429

%N a(n) = a(n-1) + sum of decimal digits of sigma(n), the sum of divisors of n.

%H Harvey P. Dale, <a href="/A071422/b071422.txt">Table of n, a(n) for n = 1..1000</a>

%t s=0; Do[s=s+Apply[Plus, IntegerDigits[DivisorSigma[1, n]]]; Print[s], {n, 1, 128}]

%t nxt[{n_,a_}]:={n+1,a+Total[IntegerDigits[DivisorSigma[1,n+1]]]}; Transpose[ NestList[nxt,{1,1},60]][[2]] (* _Harvey P. Dale_, Jan 25 2013 *)

%Y Cf. A037123, A000788, A051351.

%K base,easy,nonn

%O 1,2

%A _Labos Elemer_, May 27 2002

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Last modified August 26 03:17 EDT 2019. Contains 326324 sequences. (Running on oeis4.)