A359360 - OEIS

A359360

Length times minimum part of the integer partition with Heinz number n. Least prime index of n times number of prime indices of n.

0, 1, 2, 2, 3, 2, 4, 3, 4, 2, 5, 3, 6, 2, 4, 4, 7, 3, 8, 3, 4, 2, 9, 4, 6, 2, 6, 3, 10, 3, 11, 5, 4, 2, 6, 4, 12, 2, 4, 4, 13, 3, 14, 3, 6, 2, 15, 5, 8, 3, 4, 3, 16, 4, 6, 4, 4, 2, 17, 4, 18, 2, 6, 6, 6, 3, 19, 3, 4, 3, 20, 5, 21, 2, 6, 3, 8, 3, 22, 5, 8, 2

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OFFSET

1,3

COMMENTS

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k). A prime index of n is a number m such that prime(m) divides n.

LINKS

Table of n, a(n) for n=1..82.

FORMULA

a(n) = A001222(n) * A055396(n).

EXAMPLE

The partition with Heinz number 7865 is (6,5,5,3), so a(7865) = 4*3 = 12.

MATHEMATICA

Table[PrimeOmega[n]*PrimePi[FactorInteger[n][[1, 1]]], {n, 100}]

PROG

(PARI) a(n) = if (n==1, 0, my(f=factor(n)); bigomega(f)*primepi(f[1, 1])); \\ Michel Marcus, Dec 28 2022

CROSSREFS

Difference of A056239 and A359358.

The opposite version is A326846.

A055396 gives minimum prime index, maximum A061395.

A112798 list prime indices, length A001222, sum A056239.

A243055 subtracts the least prime index from the greatest.

A358195 gives Heinz numbers of rows of A358172, even bisection A241916.

Cf. A006141, A124010, A246277, A268192, A316413, A325352, A326836, A326837, A326844, A355534, A356958.

Sequence in context: A368572 A067399 A106737 * A323164 A363685 A339666

Adjacent sequences: A359357 A359358 A359359 * A359361 A359362 A359363

KEYWORD

nonn

AUTHOR

Gus Wiseman, Dec 28 2022

STATUS

approved