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A203719 A204521(n)^2 = floor[A055812(n)/5]: Squares which written in base 5, with some digit appended, yield another square. 0
0, 0, 0, 1, 9, 16, 64, 441, 3025, 5184, 20736, 142129, 974169, 1669264, 6677056, 45765225, 313679521, 537497856, 2149991424, 14736260449, 101003831721, 173072640400, 692290561600, 4745030099481, 32522920134769, 55728852710976, 222915410843904 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Base-5 analog of A202303.

LINKS

Table of n, a(n) for n=1..27.

FORMULA

Conjecture: a(n) = 323*a(n-4)-323*a(n-8)+a(n-12) for n>13. - Colin Barker, Sep 20 2014

Empirical g.f.: -x^4*(x^9 +9*x^8 +64*x^7 +16*x^6 +118*x^5 +118*x^4 +64*x^3 +16*x^2 +9*x +1) / ((x -1)*(x +1)*(x^2 -4*x -1)*(x^2 +1)*(x^2 +4*x -1)*(x^4 +18*x^2 +1)). - Colin Barker, Sep 20 2014

PROG

(PARI) b=5; for(n=0, 1e7, issquare(n^2\b) & print1(n^2\b, ", "))

CROSSREFS

See also A031149=sqrt(A023110) (base 10), A204502=sqrt(A204503) (base 9), A204514=sqrt(A055872) (base 8), A204516=sqrt(A055859) (base 7), A204518=sqrt(A055851) (base 6), A204520=sqrt(A055812) (base 5), A004275=sqrt(A055808) (base 4), A001075=sqrt(A055793) (base 3), A001541=sqrt(A055792) (base 2).

Sequence in context: A039785 A119575 A174468 * A198308 A167349 A267763

Adjacent sequences:  A203716 A203717 A203718 * A203720 A203721 A203722

KEYWORD

nonn,base

AUTHOR

M. F. Hasler, Jan 16 2012

EXTENSIONS

More terms from Colin Barker, Sep 20 2014

STATUS

approved

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Last modified December 13 17:30 EST 2017. Contains 295959 sequences.