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A224421 The indices of tetrahedral numbers that are also triangular. 0
0, 1, 3, 8, 20, 34 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..5.

E. T. Avanesov, Solution of a problem on figurate numbers (in Russian), Acta Arith. 12 1966/1967 pages 409-420.

EXAMPLE

The eighth tetrahedral number is 120, which is also a triangular number. Hence, 8 belongs to the sequence.

PROG

(PARI) for(n=0, 34, if(ispolygonal(n*(n+1)*(n+2)/6, 3), print1(n", "))) \\ Charles R Greathouse IV, Apr 07 2013

CROSSREFS

Cf. A027568, A102349.

Sequence in context: A195676 A027299 A321067 * A143785 A182735 A135565

Adjacent sequences:  A224418 A224419 A224420 * A224422 A224423 A224424

KEYWORD

nonn,full,fini

AUTHOR

Tanya Khovanova, Apr 06 2013

STATUS

approved

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Last modified June 24 21:50 EDT 2021. Contains 345433 sequences. (Running on oeis4.)