OFFSET
1,2
LINKS
Lucas A. Brown, Table of n, a(n) for n = 1..37
Lucas A. Brown, Python program.
Eric Weisstein's World of Mathematics, Tetrahedral Number
EXAMPLE
a(3) = 56 because 56 has 3 tetrahedral divisors {1, 4, 56} and this is the smallest such number.
PROG
(PARI) istetrah(n) = my(k=sqrtnint(6*n, 3)); k*(k+1)*(k+2)==6*n; \\ A000292
a(n) = my(k=1); while (sumdiv(k, d, istetrah(d)) != n, k++); k; \\ Michel Marcus, Nov 21 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Nov 21 2022
EXTENSIONS
a(20)-a(22) from Michel Marcus, Nov 21 2022
a(23)-a(30) from Jinyuan Wang, Nov 28 2022
a(31) from Martin Ehrenstein, Dec 02 2022
a(32) and a(33) from Lucas A. Brown, Dec 14 2022
STATUS
approved