A292850 Lucas numbers that are also generalized heptagonal numbers.

1, 4, 7, 18

Offset: 1

Author

Tomohiro Yamada, Sep 25 2017

Keywords

• nonn
• easy
• full
• fini

Comments

Intersection of A000032 and A085787.

Except 4, these are also ordinary heptagonal numbers.

All terms are shown, as confirmed by Srinivasa Rao (2002).

All (generalized) g-gonal numbers in Lucas sequences up to g=20 have been determined, see Tengely (2009).

Links

• B. Srinivasa Rao, Heptagonal Numbers in the Lucas Sequence and Diophantine Equations x^2(5x-3)^2 = 20y^2+-16, The Fibonacci Quarterly, Vol. 40, No. 4 (2002), 319-322.
• Szabolcs Tengely, Finding g-gonal numbers in recurrence sequences, Fibonacci Quarterly, vol.46/47, no.3, pp.235-240, (2009).

Crossrefs

Cf. A000032, A085787.

Cf. A248506 (triangular Lucas Numbers).