A060731 a(n) = a(n-1) + a(n - 1 minus the number of terms of a(k) == (mod 4) so far).

1, 2, 3, 4, 7, 11, 14, 25, 36, 50, 64, 89, 125, 175, 225, 314, 378, 467, 592, 817, 992, 1306, 1684, 2062, 2529, 2996, 3988, 4580, 5572, 6878, 9407, 10399, 12928, 15457, 19445, 21507, 25495, 31067, 35647, 40227, 49634, 60033, 66911, 77310, 92767

Offset

1,2

Links

Table of n, a(n) for n=1..45.

Example

a(5) = a(4) + a(4 - the number of terms congruent to 1 (mod 4) so far) = a(4) + a(4-1) = 4 + 3 = 7.

Mathematica

m[ 1 ] = 1; m[ 2 ] = 2; m[ 3 ] = 3; a[ 4 ] = 4; m[ n_Integer ] := m[ n ] = Block[ {a = b = c = d = 0}, Do[ Switch[ Mod[ m[ k ], 4 ], 0, a++, 1, b++, 2, c++, 3, d++ ], {k, 1, n - 1} ]; Switch[ Mod[ n, 4 ], 0, m[ n - 1 ] + m[ n - 1 - a ], 1, m[ n - 1 ] + m[ n - 1 - b ], 2, m[ n - 1 ] + m[ n - 1 - c ], 3, m[ n - 1 ] + m[ n - 1 - d ] ] ]; Table[ m[ n ], {n, 1, 50} ]

Crossrefs

Sequence in context: A171027 A348792 A064933 * A238492 A140827 A125621

Adjacent sequences: A060728 A060729 A060730 * A060732 A060733 A060734

Keyword

nonn

Author

Robert G. Wilson v, Apr 22 2001

Status

approved