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Search: id:A069816
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| A069816 |
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(Sum of digits of n)^2 - (sum of digits^2 of n). |
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+0
4
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| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 0, 6, 12, 18, 24, 30, 36, 42, 48, 54, 0, 8, 16, 24, 32, 40, 48, 56, 64, 72, 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 0, 12, 24, 36, 48, 60, 72, 84, 96, 108, 0, 14, 28, 42, 56, 70, 84
(list; graph; listen)
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OFFSET
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0,12
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COMMENT
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a(n) = 0 iff n is a single digit number or is a power of ten times a single digit number. - Robert G. Wilson v (rgwv(AT)rgwv.com), May 04 2002
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FORMULA
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a(n)=2*A035930(n), n<=100. a(n)=A118881(n)-A003132(n). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 23 2009]
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EXAMPLE
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n=14: sum of digits = 5, squaring gives 25; sum of squared digits of n = 1^2 + 4^2 = 17, so a(14) = 25 - 17 = 8.
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MAPLE
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A007953 := proc(n) add(d, d=convert(n, base, 10)) ; end proc: A003132:= proc(n) add(d^2, d=convert(n, base, 10)) ; end proc: A118881 := proc(n) (A007953(n))^2 ; end proc: A069816 := proc(n) A118881(n)-A003132(n) ; end proc: seq(A069816(n), n=0..80) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 23 2009]
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MATHEMATICA
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f[n_] := Plus @@ IntegerDigits[n]^2 - Plus @@ (IntegerDigits[n]^2); Table[ f[n], {n, 0, 100}]
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CROSSREFS
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Cf. A067552.
Sequence in context: A161207 A076428 A055958 this_sequence A088116 A100817 A074157
Adjacent sequences: A069813 A069814 A069815 this_sequence A069817 A069818 A069819
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KEYWORD
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nonn,base,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), May 03 2002
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EXTENSIONS
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Extended by Robert G. Wilson v (rgwv(AT)rgwv.com), May 04 2002
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