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A210853 (A210852(n)^3 + 1)/7^n, n >= 0. 5
1, 4, 608, 100082, 1033865, 147695, 363432817, 493771113103, 2362056468993, 408352474516087, 11132773648769182, 1051698129414636470, 55996715400581424222, 4972138747809482684591, 29726859239716779753649 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n) is integer because A210852(n) is one of the three solutions of X(n)^3 + 1 == 0 (mod 7^n), namely the one satisfying also X(n) == 3 (mod 7).

See the comments on A210852, and the Nagell reference given in A210848.

LINKS

Table of n, a(n) for n=0..14.

FORMULA

a(n) = (b(n)^3 + 1)/7^n, n>=0, with b(n):=A210852(n) given by a recurrence. See also a Maple program for b(n) there.

EXAMPLE

a(0) = 1/1 = 1.

a(3) = (325^3 + 1)/7^3 = 34328126/343  = 100082, (b(3) = 31^7 (mod 7^3) = 325).

CROSSREFS

Cf.  A210848, A210849 (the p=5 case).

Sequence in context: A195580 A069641 A215920 * A232620 A219892 A079103

Adjacent sequences:  A210850 A210851 A210852 * A210854 A210855 A210856

KEYWORD

nonn,easy

AUTHOR

Wolfdieter Lang, May 02 2012

STATUS

approved

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Last modified May 26 13:59 EDT 2022. Contains 354092 sequences. (Running on oeis4.)