A212537 Number of nondecreasing sequences of 4 1..n integers with every element dividing the sequence sum.

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

Offset: 1

Author

R. H. Hardin, May 20 2012

Keywords

• nonn

Comments

Row 4 of A212536.

Examples

			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
		

Links

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

Crossrefs

Cf. A212536.

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).