A216188 Number of unordered pairs of anagrammatic (positive) integers adding to n.
0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 2, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 3, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 3, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0
Offset: 1
Examples
For n = 88, the a(88) = 4 pairs are {17,71}, {26,62}, {35,53}, and {44,44}. For n = 609, the a(609) = 1 pair is {237,372}.
Links
- Christian Schulz, Table of n, a(n) for n = 1..10000 (first 1000 terms from T. D. Noe)
Programs
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Maple
getDigit := (n,k) -> floor(n/10^k) mod 10; getMaxDigit := n -> floor(log10(n)) + 1; getDigitMultiset := n -> convert([seq(getDigit(n,k),k=0..getMaxDigit(n)-1)],multiset); isAnagram := (m,n) -> evalb(getDigitMultiset(m) = getDigitMultiset(n)); A216188 := n -> convert([seq(eval(isAnagram(k,n-k),[true=1,false=0]),k=1..floor(n/2))],`+`); seq(A216188(n),n=1..50)
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Mathematica
IsAnagram[x_, y_, b_: 10] := Sort[Permutations[IntegerDigits[x, b]]] == Sort[Permutations[IntegerDigits[y, b]]]; FindAnagramSums[n_, b_: 10] := Select[Table[{k, n - k}, {k, 0, Floor[n/2]}], IsAnagram[#[[1]], #[[2]], b] &]; Table[Length[FindAnagramSums[n]], {n, 1, 200}]
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