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A225048 Numbers that cannot be expressed as n plus the sum of the squared digits of n for any integer n. 2
1, 3, 4, 5, 7, 8, 9, 10, 14, 15, 16, 18, 19, 21, 22, 25, 27, 28, 29, 32, 33, 34, 35, 37, 38, 40, 43, 46, 47, 48, 49, 50, 52, 55, 57, 60, 61, 63, 64, 65, 70, 71, 73, 74, 78, 79, 82, 84, 85, 88, 89, 91, 92, 93, 94, 97, 99, 100, 104, 106, 109, 110, 115, 120, 122 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
A natural extension of the Self or Colombian numbers (A003052).
Up to 144, there are more numbers that cannot be expressed in this way than numbers that can. Thereafter, there are always more numbers that can.
LINKS
Christian N. K. Anderson, Table of n, a(n) for n = 1..10000
EXAMPLE
26 is not in the sequence, because 21+2^2+1^2=26. However, no such solution exists for 25 or 27.
MATHEMATICA
nn=122; Complement[Range[nn], Table[n+Total[IntegerDigits[n]^2], {n, nn}]] (* Jayanta Basu, May 05 2013 *)
PROG
(R) digsqsum<-function(x) sum(as.numeric(unlist(strsplit(as.character(x), split="")))^2)
which(is.na(match(1:1000, 1:1000+sapply(1:1000, digsqsum)))
CROSSREFS
Sequence in context: A241687 A169757 A051374 * A357129 A116590 A024355
KEYWORD
nonn,base
AUTHOR
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)