A071938 - OEIS

A071938

Binomial(max(n,R(n)),min(n,R(n))) where R(n) is the reversal of n.

1, 1, 1, 1, 1, 1, 1, 1, 1, 10, 1, 293930, 206253075, 35240152720, 3188675231420, 202802465047245, 10358022441395860, 456703981505085600, 18150420051920130975, 190, 293930, 1, 28048800, 353697121050

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OFFSET

1,10

COMMENTS

a(n) = Binomial(n,reverse(n)) if n >= reverse(n); = Binomial(reverse(n),n) if n < reverse(n).

a(n) = 1 if n is a palindrome. a(n) = n if n = 10^k. - Amarnath Murthy, Jul 14 2005

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

a(10) = binomial(10,1) = 10, a(11) = 1, a(12) = binomial(21,12) = 293930.

MAPLE

R:=proc(n) local nn, nnn: nn:=convert(n, base, 10): add(nn[nops(nn)+1-j]*10^(j-1), j=1..nops(nn)) end: seq(binomial(max(n, R(n)), min(n, R(n))), n=1..27); # Emeric Deutsch, Jul 16 2005

MATHEMATICA

bmm[n_]:=Module[{ir=IntegerReverse[n]}, Binomial[Max[n, ir], Min[n, ir]]]; Array[ bmm, 30] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 13 2020 *)

CROSSREFS

Sequence in context: A280410 A288296 A288020 * A261942 A359734 A057603

Adjacent sequences: A071935 A071936 A071937 * A071939 A071940 A071941

KEYWORD

base,nonn

AUTHOR

Joseph L. Pe, Jun 14 2002

EXTENSIONS

Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, Jun 23 2007

STATUS

approved