

A144941


Numbers n such that 6*n1 = A144796(n).


1



1, 36, 753, 41348, 868769, 47715364, 1002558481, 55063488516, 1156951618113, 63543218031908, 1335121164743729, 73328818545333124, 1540728667162644961, 84621393058096392996, 1777999546784527541073, 97653014260224692184068
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OFFSET

1,2


COMMENTS

Also the index of a pentagonal number which is equal to the sum of two consecutive pentagonal numbers.  Colin Barker, Dec 22 2014


LINKS

Colin Barker, Table of n, a(n) for n = 1..653
Index entries for linear recurrences with constant coefficients, signature (1,1154,1154,1,1).


FORMULA

For the odd and even indices respectively the same recurrence is obtained: a(n+2) = 1154*a(n+1)a(n)192.
We have also: a(n+2 = 577*a(n+1)96+68*sqrt((72*a(n)^224*a(n)32)).
G.f. x*(1+35*x437*x^2+205*x^3+4*x^4) / ((x1)*(x^234*x+1)*(x^2+34*x+1)).  R. J. Mathar, Nov 27 2011


EXAMPLE

a(1) = 1 because 6*11 = 5 = A144796(1).


MATHEMATICA

LinearRecurrence[{1, 1154, 1154, 1, 1}, {1, 36, 753, 41348, 868769}, 30] (* Harvey P. Dale, Dec 27 2018 *)


PROG

(PARI) Vec(x*(1+35*x437*x^2+205*x^3+4*x^4) / ((x1)*(x^234*x+1)*(x^2+34*x+1)) + O(x^100)) \\ Colin Barker, Dec 22 2014


CROSSREFS

Cf. A133301, A144796, A144797.
Sequence in context: A049434 A215768 A320821 * A036084 A265194 A280123
Adjacent sequences: A144938 A144939 A144940 * A144942 A144943 A144944


KEYWORD

easy,nonn


AUTHOR

Richard Choulet, Sep 26 2008


EXTENSIONS

a(6) corrected and sequence extended by R. J. Mathar, Nov 27 2011


STATUS

approved



