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A079168 Weighted quadratic roundness of n. If n=p_1^e_1...p^k_e^k, then a(n) = e_1 + (2^2 * e_2) + ... + (k^2 * e_k). Note that p_i<p_j, i<j, is assumed. 3
0, 1, 1, 2, 1, 5, 1, 3, 2, 5, 1, 6, 1, 5, 5, 4, 1, 9, 1, 6, 5, 5, 1, 7, 2, 5, 3, 6, 1, 14, 1, 5, 5, 5, 5, 10, 1, 5, 5, 7, 1, 14, 1, 6, 6, 5, 1, 8, 2, 9, 5, 6, 1, 13, 5, 7, 5, 5, 1, 15, 1, 5, 6, 6, 5, 14, 1, 6, 5, 14, 1, 11, 1, 5, 9, 6, 5, 14, 1, 8, 4, 5, 1, 15, 5, 5, 5, 7, 1, 18, 5, 6, 5, 5, 5, 9, 1, 9, 6, 10 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

EXAMPLE

a(1) = 0 (an empty sum).

a(10) = 5 as 10 = 2*5, therefore a(10) = (1^2)*1 + (2^2)*1 = 5

a(45) = 6 as 45 = 3^2 * 5, therefore a(45) = (1^2)*2 + (2^2)*1 = 6.

a(50) = 5 as 50 = 2^1 * 5^2, therefore a(50) = (1^2)*1 + (2^2)*2 = 9.

a(250) = 7 as 250 = 2^1 * 5^3, therefore a(250) = (1^2)*1 + (2^2)*3 = 13.

PROG

(PARI) weightedroundness2(n)=local(f, fl, s); f=factor(n); fl=length(f[, 1]); s=0; for (i=1, fl, s=s+i^2*f[, 2][i]); s alias(wr2, weightedroundness2) for (j=2, 500, print1(wr2(j)", "))

CROSSREFS

Cf. A079167, A079169, A001222.

Sequence in context: A132601 A047818 A055972 * A055205 A161686 A289621

Adjacent sequences:  A079165 A079166 A079167 * A079169 A079170 A079171

KEYWORD

nonn

AUTHOR

Jon Perry, Dec 31 2002

EXTENSIONS

a(1) = 0 prepended and more examples by Antti Karttunen, May 31 2017

STATUS

approved

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Last modified February 16 21:59 EST 2019. Contains 320200 sequences. (Running on oeis4.)