A004795 - OEIS

A004795

Least positive unitary linear combination of distinct numbers in row n of Pascal's triangle; i.e., least positive sum of form d(0)C(n-1,0) + d(1)C(n-1,1) + ...+ d(m)C(n-1,m), d(i)=+-1, m = floor((n+1)/2).

1, 1, 1, 2, 1, 4, 2, 6, 5, 2, 22, 10, 64, 64, 102, 126, 33, 220, 1902, 132, 2202, 604, 2120, 942, 22768, 4044, 234638, 7436, 614482, 8264, 107008, 23776, 11154697, 4336, 1152138, 129812, 37815814, 245272, 23068832, 341506, 12223534, 427260, 53970758

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

LINKS

Table of n, a(n) for n=1..43.

PROG

(PARI) padbin(n, len) = my(b = binary(n)); while(length(b) < len, b = concat(0, b); ); b;

a(n) = m = (n+1)\2; nb = 2^(m+1); lps = 0; v = vector(m, i, binomial(n-1, i-1)); for (i = 1, nb-1, vb = padbin(i, m+1); s = sum(k = 1, m, if (vb[k], v[k], -v[k])); if ((s>0), if (lps == 0, lps = s, if (s < lps, lps = s; ); )); ); lps; \\ Michel Marcus, Sep 30 2013

CROSSREFS

Sequence in context: A359907 A244515 A154280 * A161268 A176837 A339241

Adjacent sequences: A004792 A004793 A004794 * A004796 A004797 A004798

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

a(22)-a(43) from Michel Marcus, Sep 30 2013

STATUS

approved