A358539 a(n) is the smallest number with exactly n divisors that are n-gonal numbers.

6, 36, 210, 1260, 6426, 3360, 351000, 207900, 3749460, 1153152, 15036840, 204204000, 213825150, 11737440, 91797866160, 1006485480, 2310808500, 4966241280, 22651328700, 325269404460, 14266470332400, 11203920000, 256653797400, 45843256859400, 59207908359600, 46822406400

Offset

3,1

Links

Table of n, a(n) for n=3..28.

Lucas A. Brown, Python program.

Eric Weisstein's World of Mathematics, Polygonal Number

Index entries for sequences related to divisors of numbers

Example

a(5) = 210 because 210 has 5 pentagonal divisors {1, 5, 35, 70, 210} and this is the smallest such number.

Prog

(PARI) a(n) = my(k=1); while (sumdiv(k, d, ispolygonal(d, n)) != n, k++); k; \\ Michel Marcus, Nov 21 2022

Crossrefs

Cf. A005179, A130279, A130317, A356132, A358540, A358541.

Sequence in context: A096979 A269464 A123887 * A105492 A052748 A292297

Adjacent sequences: A358536 A358537 A358538 * A358540 A358541 A358542

Keyword

nonn

Author

Ilya Gutkovskiy, Nov 21 2022

Extensions

a(12)-a(13) from Michel Marcus, Nov 21 2022

a(14)-a(16) from Daniel Suteu, Dec 04 2022

a(17)-a(28) from Martin Ehrenstein, Dec 05 2022

Status

approved