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A273374 Squares ending in digit 9. 2
9, 49, 169, 289, 529, 729, 1089, 1369, 1849, 2209, 2809, 3249, 3969, 4489, 5329, 5929, 6889, 7569, 8649, 9409, 10609, 11449, 12769, 13689, 15129, 16129, 17689, 18769, 20449, 21609, 23409, 24649, 26569, 27889, 29929, 31329, 33489, 34969, 37249, 38809 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1).

FORMULA

G.f.: x*(9 + 40*x + 102*x^2 + 40*x^3 + 9*x^4)/((1 + x)^2*(1 - x)^3).

a(n) = 6 + (50*(n-1)*n - 5*(2*n-1)*(-1)^n + 1)/2.

a(n) = A063226(n)^2. - Seiichi Manyama, May 25 2016

MATHEMATICA

Table[6 + (50 (n - 1) n - 5 (2 n - 1) (-1)^n + 1)/2, {n, 1, 50}]

PROG

(MAGMA) /* By definition: */ [n^2: n in [0..200] | Modexp(n, 2, 10) eq 9];

(MAGMA) [6+(50*(n-1)*n-5*(2*n-1)*(-1)^n+1)/2: n in [1..50]];

CROSSREFS

Cf. A000290, A016754, A063226.

Cf. A017377 (numbers ending in 9), A017379 (cubes ending in 9).

Cf. similar sequences listed in A273373.

Sequence in context: A212503 A295019 A164343 * A020245 A082608 A058031

Adjacent sequences:  A273371 A273372 A273373 * A273375 A273376 A273377

KEYWORD

nonn,base,easy

AUTHOR

Vincenzo Librandi, May 21 2016

EXTENSIONS

Corrected and extended by Bruno Berselli, May 21 2016

STATUS

approved

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Last modified August 3 15:29 EDT 2021. Contains 346438 sequences. (Running on oeis4.)