A385917 -id:A385917 - cp's OEIS frontend

A386549 Indices of hexagonal numbers that are one-sixth of another hexagonal number.

0, 1, 72, 7031, 688942, 67509261, 6615218612, 648223914691, 63519328421082, 6224245961351321, 609912584884008352, 59765209072671467151, 5856380576536919772422, 573865531291545466230181, 56232965685994918770785292, 5510256771696210494070728411, 539948930660542633500160598962

Offset: 1

Kelvin Voskuijl, Jul 25 2025

			72 is in this sequence because the 72th hexagonal number (10296) is one-sixth of another hexagonal number.

Index entries for linear recurrences with constant coefficients, signature (99,-99,1).

Cf. A000384, A385917, A386550.

G.f.: x^2 * (1 - 27*x + 2*x^2) / (1 - 99*x + 99*x^2 - x^3). - Jinyuan Wang, Jul 26 2025

More terms from Jinyuan Wang, Jul 26 2025

A386550 Indices of hexagonal numbers that are six times another hexagonal number.

Original entry on oeis.org

0, 2, 176, 17222, 1687556, 165363242, 16203910136, 1587817830062, 155589943435916, 15246226638889682, 1493974620667752896, 146394266598800894102, 14345144152061819869076, 1405677732635459546275322, 137742072654122973715112456, 13497317442371415964534745342

Offset: 1

Kelvin Voskuijl, Jul 25 2025

			176 is in this sequence because the 176th hexagonal number (61776) is six times another hexagonal number.

Index entries for linear recurrences with constant coefficients, signature (99,-99,1).

Cf. A000384, A269551, A385917, A386549.

a(n) = (3*A269551(n-2) - 7)/4 for n>=2. - Hugo Pfoertner, Jul 26 2025

G.f.: 2*x^2*(1 - 11*x - 2*x^2)/((1 - x)*(1 - 98*x + x^2)). - Stefano Spezia, Jul 27 2025

More terms from Jinyuan Wang, Jul 26 2025

cp's OEIS Frontend

A386549 Indices of hexagonal numbers that are one-sixth of another hexagonal number.

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