# #divisors

One day, one decomposition

A006532: Numbers whose sum of divisors is a square

3D graph #threejs #webGL ➡️ https://decompwlj.com/3Dgraph/A006532.html

2D graph, first 500 terms ➡️ https://decompwlj.com/2Dgraph500terms/A006532.html

#decompwlj #math #mathematics #sequence #OEIS #javascript #php #3D #numbers #sum #divisors #square #graph

One day, one decomposition

A006073: Numbers n such that n, n+1 and n+2 all have same number of distinct prime divisors

3D graph #threejs #webGL ➡️ https://decompwlj.com/3Dgraph/A006073.html

2D graph, first 500 terms ➡️ https://decompwlj.com/2Dgraph500terms/A006073.html

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One day, one decomposition

A005279: Numbers having divisors d,e with d < e < 2*d

3D graph #threejs #webGL ➡️ https://decompwlj.com/3Dgraph/A005279.html

2D #graph, first 500 terms ➡️ https://decompwlj.com/2Dgraph500terms/A005279.html

#decompwlj #math #mathematics #sequence #OEIS #javascript #php #3D #numbers #divisors

Abuse of the fact that the #deck #size has many #divisors: 126 = 2 * 3^2 * 7 (12 divisors); without the #star #cards, 120 = 2^3 * 3 * 5 (16 divisors).

I will start, adapting #BlackJack: the cards must add to 69 (a titillating number) instead of 21. Each player starts with 4 cards at hand, instead of 1, to speed up play: in average, about 7 cards are needed to reach 69. The betting, if present, is the same as the original game.

One day, one decomposition

A003601: Numbers n such that the average of the divisors of n is an integer: sigma_0(n) divides sigma_1(n). Alternatively, tau(n) (A000005(n)) divides sigma(n) (A000203(n))

3D graph #threejs #webGL ➡️ https://decompwlj.com/3Dgraph/A003601.html

2D graph, first 500 terms ➡️ https://decompwlj.com/2Dgraph500terms/A003601.html

#decompwlj #math #mathematics #sequence #OEIS #javascript #php #3D #numbers #average #divisors #integer #sigma #tau #graph