A249731 Number of multiples of 4 on row n of Pascal's triangle minus the number of multiples of 9 on the same row: a(n) = A249732(n) - A249733(n).

0, 0, 0, 0, 2, 0, 1, 0, 6, -2, 0, 0, 3, 0, 3, -2, 13, 12, -1, 2, 13, -2, 3, 0, 15, 12, 11, -20, -4, -12, -12, -14, 21, 14, 20, 24, 1, 2, 11, -4, 20, 20, 11, 6, 29, -18, -4, -6, 22, 26, 32, 18, 32, 22, -25, -34, 9, -4, -1, -6, 9, 0, 15, -50, 25, 36, 23, 32, 49, 32, 44, 48, 13, 26, 43, 10, 41, 40, 31, 24, 73, -12

Offset

0,5

Links

Antti Karttunen, Table of n, a(n) for n = 0..6561

Formula

a(n) = A249732(n) - A249733(n).

Prog

(Scheme) (define (A249731 n) (- (A249732 n) (A249733 n)))
(Python)
import re
from gmpy2 import digits
def A249731(n):
    s = digits(n, 3)
    n1 = s.count('1')
    n2 = s.count('2')
    n01 = s.count('10')
    n02 = s.count('20')
    n11 = len(re.findall('(?=11)', s))
    n12 = s.count('21')
    return (((3*(n01+1)+(n02<<2)+n12<<2)+3*n11)*(3**n2<<n1)//12)-(2+((n>>1)&~n).bit_count()<<n.bit_count()>>1) # Chai Wah Wu, Jul 24 2025

Crossrefs

Cf. A007318, A034931, A095143, A249723, A249732, A249733.

Sequence in context: A166378 A249820 A136579 * A335125 A335022 A249732

Adjacent sequences: A249728 A249729 A249730 * A249732 A249733 A249734

Keyword

sign

Author

Antti Karttunen, Nov 05 2014

Status

approved