

A307174


Numbers that are both triangular and icosahedral.


1




OFFSET

1,3


COMMENTS

The list is probably finite, like the list of triangular and tetrahedral numbers (A027568).
It would appear that the similar sequence of pentagonaldodecahedral numbers contains only the trivial cases of 0 and 1.
Intersection of A000217 and A006564.  A.H.M. Smeets, Aug 19 2019


LINKS

Table of n, a(n) for n=1..4.


MATHEMATICA

Intersection[Accumulate[Range[0, 199]], Table[n (5n^2  5n + 2)/2, {n, 0, 99}]] (* Alonso del Arte, Jul 10 2019 *)


PROG

(PARI) lista(nn) = for (n=0, nn, if (ispolygonal(k=n*(5*n^2  5*n + 2)/2, 3), print1(k, ", "))); \\ Michel Marcus, Jul 10 2019


CROSSREFS

Cf. A000217, A006564, A027568, A309009.
Sequence in context: A252299 A203063 A237294 * A278732 A278434 A198469
Adjacent sequences: A307171 A307172 A307173 * A307175 A307176 A307177


KEYWORD

nonn,fini,more,bref


AUTHOR

William C. Laursen, Jul 09 2019


STATUS

approved



