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Antti Karttunen, <a href="/A333805/b333805.txt">Table of n, a(n) for n = 1..65537</a>

0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 3, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 1, 2, 1, 1, 3, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 2, 2, 1, 1, 3, 1, 1, 3, 1, 2, 2, 1, 1, 2, 3, 1, 2, 1, 1, 3, 1, 2, 2, 1, 2, 2, 1, 1, 3, 2, 1, 2, 1, 1, 4, 2, 1, 2, 1, 2, 2, 1, 2, 3, 2, 1, 2, 1, 1, 4

(PARI) A333805(n) = sumdiv(n, d, (d%2)&&((d*d)<n)); \\ Antti Karttunen, Nov 02 2022

Data section extended up to a(105) by Antti Karttunen, Nov 02 2022

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A020639 selects the smallest prime factor.

A020639 selects the smallest prime factor.

A055396A020639 selects the smallest prime indexfactor.

A061395A006530 selects the greatest prime indexfactor.

The case of squarefree instead of prime divisors is A341596.

The case of prime-power instead of odd divisors is A341677.

A055396 selects the leastsmallest prime index.

A033677 selects the leastsmallest superior divisor.

A063538/A063539 have/lack a superior prime divisor.

A063962 counts inferior prime divisors.

A116883/A116882 have/lack an odd superior divisor.

Cf. A001248, A051283, A063538/A063539, A063962, A116883/A116882, A300272, A333807, A333809, A340832.