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

2, 8, 18, 32, 50, 72, 98, 101, 123, 128, 149, 162, 179, 213, 251, 293, 339, 389, 404, 443, 446, 492, 542, 596, 654, 716, 782, 852, 909, 926, 971, 1037, 1107, 1181, 1259, 1341, 1427, 1517, 1611, 1616, 1698, 1784, 1874, 1968, 2066, 2168, 2274, 2384, 2498, 2525

Offset

1,1

Comments

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.

Links

Christian N. K. Anderson, Table of n, a(n) for n = 1..10000

Christian N. K. Anderson, Ulam Spiral of terms 1 to 500.

Example

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

Mathematica

Table[n^2+Total[IntegerDigits[n]^2], {n, 100}]//Union (* Harvey P. Dale, Jan 25 2021 *)

Prog

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

Crossrefs

Cf. A171613, A062028, A007770.

Sequence in context: A357851 A067051 A074629 * A001105 A361905 A336489

Adjacent sequences: A209300 A209301 A209302 * A209304 A209305 A209306

Keyword

nonn,base

Author

Christian N. K. Anderson, Apr 22 2013

Status

approved