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A294688 Palindromes in Narayana's cows sequence (A000930). 1
1, 2, 3, 4, 6, 9, 88, 595 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

595 is probably the last term.

LINKS

Table of n, a(n) for n=1..8.

MAPLE

R:=proc(w) local k, x; x:=convert(w, base, 10);

add(x[nops(x)-k+1]*10^(k-1), k=1..nops(x)); end:

P:=proc(q) local a, k, n; for n from 2 to q do

a:=add(binomial(n-2*k, k), k=0..floor(n/3));

if a=R(a) then print(a); fi; od; end: P(10^5); # Paolo P. Lava, Nov 07 2017

# Alternatively:

a := proc(n) if n < 4 then n else

simplify(hypergeom([-n/3, (1-n)/3, (-1-n)/3], [-n/2, (-1-n)/2], -27/4));

convert(%, base, 10); ListTools:-Reverse(%);

if %% = % then add(%[k]*10^(k-1), k=1..nops(%)) else NULL fi fi end:

seq(a(n), n=1..200); # Peter Luschny, Nov 07 2017

CROSSREFS

Cf. A000930, A002113, A045504, A055391.

Sequence in context: A295394 A081419 A108858 * A094859 A267102 A122397

Adjacent sequences:  A294685 A294686 A294687 * A294689 A294690 A294691

KEYWORD

nonn,base,more,hard

AUTHOR

Chai Wah Wu, Nov 06 2017

STATUS

approved

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Last modified April 11 14:14 EDT 2021. Contains 342886 sequences. (Running on oeis4.)