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 A241918 Table of partitions where the ordering is based on the modified partial sums of the exponents of primes in the prime factorization of n. 15
 0, 1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 1, 1, 3, 1, 2, 2, 2, 2, 1, 1, 1, 1, 1, 3, 3, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 2, 2, 4, 1, 1, 1, 1, 1, 1, 1, 2, 3, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 3, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 4, 1, 1, 2, 2, 2, 2, 2, 2, 2, 1, 3, 3, 3, 3, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 COMMENTS a(1) = 0 by convention (stands for an empty partition). For n >= 2, A203623(n-1)+2 gives the index to the beginning of row n and for n>=1, A203623(n)+1 is the index to the end of row n. LINKS Antti Karttunen, Table of n, a(n) for n = 1..10081; rows 1..521 flattened. Marc LeBrun's original "crazy order" mapping for partitions (Copy of Marc's Jan 11 2006 message in OEIS Wiki) FORMULA If A241914(n)=0 and A241914(n+1)=0, a(n) = A067255(n); otherwise, if A241914(n)=0 and A241914(n+1)>0, a(n) = A067255(n)+1; otherwise, if A241914(n)>0 and A241914(n+1)=0, a(n) = a(n-1) + A067255(n) - 1, otherwise, when A241914(n)>0 and A241914(n+1)>0, a(n) = a(n-1) + A067255(n). EXAMPLE Table begins: Row     Partition [ 1]    0;         (stands for empty partition) [ 2]    1;         (as 2 = 2^1) [ 3]    1,1;       (as 3 = 2^0 * 3^1) [ 4]    2;         (as 4 = 2^2) [ 5]    1,1,1;     (as 5 = 2^0 * 3^0 * 5^1) [ 6]    2,2;       (as 6 = 2^1 * 3^1) [ 7]    1,1,1,1;   (as 7 = 2^0 * 3^0 * 5^0 * 7^1) [ 8]    3;         (as 8 = 2^3) [ 9]    1,2;       (as 9 = 2^0 * 3^2)     2,2,2;     (as 10 = 2^1 * 3^0 * 5^1)     1,1,1,1,1;     3,3;     1,1,1,1,1,1;     2,2,2,2;     1,2,2;     (as 15 = 2^0 * 3^1 * 5^1)     4;     1,1,1,1,1,1,1;     2,3;       (as 18 = 2^1 * 3^2) etc. If n is 2^k (k>=1), then the partition is a singleton {k}, otherwise, add one to the exponent of 2 (= A007814(n)), and subtract one from the exponent of the greatest prime dividing n (= A071178(n)), leaving the intermediate exponents as they are, and then take partial sums of all, thus resulting for e.g. 15 = 2^0 * 3^1 * 5^1 the modified sequence of exponents {0+1, 1, 1-1} -> {1,1,0}, whose partial sums {1,1+1,1+1+0} -> {1,2,2} give the corresponding partition at row 15. MATHEMATICA Table[If[n == 1, {0}, Function[s, Function[t, Accumulate[If[Length@ t < 2, {0}, Join[{1}, ConstantArray[0, Length@ t - 2], {-1}]] + ReplacePart[t, Map[#1 -> #2 & @@ # &, s]]]]@ ConstantArray[0, Transpose[s][[1, -1]]]][FactorInteger[n] /. {p_, e_} /; p > 0 :> {PrimePi@ p, e}]], {n, 31}] // Flatten (* Michael De Vlieger, May 12 2017 *) PROG (Scheme, with Antti Karttunen's IntSeq-library) (definec (A241918 n) (cond ((zero? (A241914 n)) (if (zero? (A241914 (+ n 1))) (A067255 n) (+ 1 (A067255 n)))) ((zero? (A241914 (+ 1 n))) (+ (A241918 (- n 1)) (- (A067255 n) 1))) (else (+ (A241918 (- n 1)) (A067255 n))))) CROSSREFS For n>=2, the length of row n is given by A061395(n). Cf. also A067255, A203623, A241914. Other tables of partitions: A112798 (also based on prime factorization), A227739, A242628 (encoded in the binary representation of n), and A036036-A036037, A080576-A080577, A193073 for various lexicographical orderings. Permutation A241909 maps between order of partitions employed here, and the order employed in A112798. Permutation A122111 is induced when partitions in this list are conjugated. A241912 gives the row numbers for which the corresponding rows in A112798 and here are the conjugate partitions of each other. Sequence in context: A316789 A319661 A320015 * A276317 A289944 A055215 Adjacent sequences:  A241915 A241916 A241917 * A241919 A241920 A241921 KEYWORD nonn,tabf AUTHOR Antti Karttunen, May 03 2014, based on Marc LeBrun's Jan 11 2006 message on SeqFan mailing list. STATUS approved

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Last modified August 3 17:26 EDT 2020. Contains 336200 sequences. (Running on oeis4.)