login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A252770 Numbers n such that the heptagonal number H(n) is equal to the sum of the pentagonal numbers P(m), P(m+1), P(m+2) and P(m+3) for some m. 2
148, 9155, 567444, 35172355, 2180118548, 135132177603, 8376014892820, 519177791177219, 32180647038094740, 1994680938570696643, 123638037544345097108, 7663563646810825324035, 475017308064726824993044, 29443409536366252324244675, 1825016373946642917278176788 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also positive integers y in the solutions to 12*x^2-5*y^2+32*x+3*y+36 = 0, the corresponding values of x being A252769.

LINKS

Colin Barker, Table of n, a(n) for n = 1..557

Index entries for linear recurrences with constant coefficients, signature (63,-63,1).

FORMULA

a(n) = 63*a(n-1)-63*a(n-2)+a(n-3).

G.f.: -x*(3*x^2-169*x+148) / ((x-1)*(x^2-62*x+1)).

EXAMPLE

148 is in the sequence because H(148) = 54538 = 13207+13490+13776+14065 = P(94)+P(95)+P(96)+P(97).

PROG

(PARI) Vec(-x*(3*x^2-169*x+148)/((x-1)*(x^2-62*x+1)) + O(x^100))

CROSSREFS

Cf. A000326, A000566, A252769.

Sequence in context: A224372 A185478 A210159 * A035822 A221349 A178083

Adjacent sequences:  A252767 A252768 A252769 * A252771 A252772 A252773

KEYWORD

nonn,easy

AUTHOR

Colin Barker, Dec 21 2014

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 18 11:37 EDT 2021. Contains 345098 sequences. (Running on oeis4.)