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A212537 Number of nondecreasing sequences of 4 1..n integers with every element dividing the sequence sum 1
1, 3, 5, 10, 12, 17, 18, 23, 26, 30, 31, 40, 41, 43, 47, 52, 53, 59, 60, 67, 70, 72, 73, 82, 84, 86, 89, 94, 95, 103, 104, 109, 111, 113, 115, 125, 126, 128, 130, 137, 138, 144, 145, 150, 155, 157, 158, 167, 168, 172, 174, 179, 180, 186, 188, 193, 195, 197, 198, 210, 211, 213 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 4 of A212536

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 2*a(n-1) -2*a(n-2) -a(n-3) +4*a(n-4) -5*a(n-5) +6*a(n-7) -9*a(n-8) +3*a(n-9) +6*a(n-10) -12*a(n-11) +7*a(n-12) +4*a(n-13) -13*a(n-14) +11*a(n-15) -11*a(n-17) +13*a(n-18) -4*a(n-19) -7*a(n-20) +13*a(n-21) -8*a(n-22) -a(n-23) +10*a(n-24) -10*a(n-25) +5*a(n-26) +5*a(n-27) -10*a(n-28) +10*a(n-29) -a(n-30) -8*a(n-31) +13*a(n-32) -7*a(n-33) -4*a(n-34) +13*a(n-35) -11*a(n-36) +11*a(n-38) -13*a(n-39) +4*a(n-40) +7*a(n-41) -12*a(n-42) +6*a(n-43) +3*a(n-44) -9*a(n-45) +6*a(n-46) -5*a(n-48) +4*a(n-49) -a(n-50) -2*a(n-51) +2*a(n-52) -a(n-53)

EXAMPLE

Some solutions for n=8

..4....2....6....7....5....2....1....3....2....1....3....2....4....1....1....1

..4....6....6....7....5....2....2....3....2....2....3....3....6....1....1....1

..8....8....6....7....5....4....3....6....4....2....3....3....6....1....2....4

..8....8....6....7....5....8....6....6....4....5....3....4....8....3....4....6

CROSSREFS

Sequence in context: A336531 A285415 A275668 * A047389 A263652 A285679

Adjacent sequences:  A212534 A212535 A212536 * A212538 A212539 A212540

KEYWORD

nonn

AUTHOR

R. H. Hardin May 20 2012

STATUS

approved

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Last modified December 2 18:11 EST 2021. Contains 349445 sequences. (Running on oeis4.)