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A209303 Numbers of the form x^2 + SumOfSquaredDigits(x). 4

%I #15 Jan 25 2021 19:33:20

%S 2,8,18,32,50,72,98,101,123,128,149,162,179,213,251,293,339,389,404,

%T 443,446,492,542,596,654,716,782,852,909,926,971,1037,1107,1181,1259,

%U 1341,1427,1517,1611,1616,1698,1784,1874,1968,2066,2168,2274,2384,2498,2525

%N Numbers of the form x^2 + SumOfSquaredDigits(x).

%C Note that early terms are not always produced in order. For example, 162 is produced by x=9, but is the 12th term in the sequence. The last out-of-order term is a(30)=926, produced when x=29.

%H Christian N. K. Anderson, <a href="/A209303/b209303.txt">Table of n, a(n) for n = 1..10000</a>

%H Christian N. K. Anderson, <a href="/A209303/a209303.gif">Ulam Spiral</a> of terms 1 to 500.

%e 251 is in the sequence, because 15^2 + (1^2 + 5^2) = 251.

%t Table[n^2+Total[IntegerDigits[n]^2],{n,100}]//Union (* _Harvey P. Dale_, Jan 25 2021 *)

%o (R) sort((1:10000)^2+vapply(1:10000,sum(as.numeric(unlist(strsplit(as.character(as.bigz(x)),split="")))^2),1))

%Y Cf. A171613, A062028, A007770.

%K nonn,base

%O 1,1

%A _Christian N. K. Anderson_, Apr 22 2013

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Last modified April 17 18:43 EDT 2024. Contains 371765 sequences. (Running on oeis4.)