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A257989 The crank of the partition having Heinz number n. 2
-1, 2, -2, 3, 0, 4, -3, 2, 0, 5, -2, 6, 0, 3, -4, 7, 1, 8, -1, 4, 0, 9, -3, 3, 0, 2, -1, 10, 1, 11, -5, 5, 0, 4, -2, 12, 0, 6, -3, 13, 1, 14, -1, 3, 0, 15, -4, 4, 1, 7, -1, 16, 2, 5, -2, 8, 0, 17, -1, 18, 0, 4, -6, 6, 1, 19, -1, 9, 1, 20, -3, 21, 0, 3, -1, 5, 1, 22, -4, 2, 0, 23, -1, 7, 0, 10, -2, 24, 2, 6, -1 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

COMMENTS

The crank of a partition p is defined to be (i) the largest part of p if there is no 1 in p and (ii) (the number of parts larger than the number of 1's) minus (the number of 1's).

We define the Heinz number of a partition p = [p_1, p_2, ..., p_r] as Product(p_j-th prime, j=1...r) (concept used by Alois P. Heinz in A215366 as an "encoding" of a partition). For example, for the partition [1, 1, 2, 4, 10] we get 2*2*3*7*29 = 2436.

In the Maple program the subprogram B yields the partition with Heinz number n, the subprogram b yields the number of 1's in the partition with Heinz number n and the subprogram c yields the number of parts that are larger than the number of 1's in the partition with the Heinz number n.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 2..10000

G. E. Andrews and F. Garvan, Dyson's crank of a partition, Bull. Amer. Math. Soc., 18 (1988), 167-171.

B. C. Berndt, H. H. Chan, S. H. Chan, W.-C. Liaw, Cranks and dissections in Ramanujan's lost notebook, J. Comb. Theory, Ser. A, 109, 2005, 91-120.

B. C. Berndt, H. H. Chan, S. H. Chan, W.-C. Liaw, Cranks - really the final problem, Ramanujan J., 23, 2010, 3-15.

G. E. Andrews, K. Ono, Ramanujan's congruences and Dyson's crank, Proc. Natl. Acad. Sci. USA, 102, 2005, 15277.

K. Mahlburg, Partition congruences and the Andrews-Garvan-Dyson crank, Proc. Natl. Acad. Sci. USA, 102, 2005, 15373-15376.

Wikipedia, Crank of a partition

EXAMPLE

a(12) = - 2 because the partition with Heinz number 12 = 2*2*3 is [1,1,2], the number of parts larger than the number of 1's is 0 and the number of 1's is 2; 0 - 2 = -2.

a(945) = 4 because the partition with Heinz number 945 = 3^3 * 5 * 7 is [2,2,2,3,4] which has no part 1; the largest part is 4.

MAPLE

with(numtheory): a := proc (n) local B, b, c: B := proc (n) local nn, j, m: nn := op(2, ifactors(n)): for j to nops(nn) do m[j] := op(j, nn) end do; [seq(seq(pi(op(1, m[i])), q = 1 .. op(2, m[i])), i = 1 .. nops(nn))] end proc: b := proc (n) if `mod`(n, 2) = 1 then 0 else 1+b((1/2)*n) end if end proc: c := proc (n) local b, B, ct, i: b := proc (n) if `mod`(n, 2) = 1 then 0 else 1+b((1/2)*n) end if end proc: B := proc (n) local nn, j, m: nn := op(2, ifactors(n)): for j to nops(nn) do m[j] := op(j, nn) end do: [seq(seq(pi(op(1, m[i])), q = 1 .. op(2, m[i])), i = 1 .. nops(nn))] end proc: ct := 0: for i to bigomega(n) do if b(n) < B(n)[i] then ct := ct+1 else  end if end do: ct end proc: if b(n) = 0 then max(B(n)) else c(n)-b(n) end if end proc: seq(a(n), n = 2 .. 150);

MATHEMATICA

B[n_] := Module[{nn, j, m}, nn =  FactorInteger[n]; For[j = 1, j <= Length[nn], j++, m[j] = nn[[j]]]; Flatten[Table[Table[PrimePi[m[i][[1]]], {q, 1, m[i][[2]]}], {i, 1, Length[nn]}]]];

b[n_] := b[n] = If[OddQ[n], 0, 1 + b[n/2]];

c[n_] := Module[{ct, i}, ct = 0; For[i = 1, i <= PrimeOmega[n], i++, If[ b[n] < B[n][[i]], ct++]]; ct];

a[n_] := If[b[n] == 0, Max[B[n]], c[n] - b[n]];

Table[a[n], {n, 2, 100}] (* Jean-Fran├žois Alcover, Apr 25 2017, after Emeric Deutsch *)

CROSSREFS

Cf. A215366, A257988.

Sequence in context: A035143 A035173 A263254 * A095201 A272143 A095058

Adjacent sequences:  A257986 A257987 A257988 * A257990 A257991 A257992

KEYWORD

sign

AUTHOR

Emeric Deutsch, May 18 2015

STATUS

approved

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Last modified September 23 09:03 EDT 2020. Contains 337298 sequences. (Running on oeis4.)