A275018 a(n) = A278846(n)/8.

0, 0, 0, 0, 0, 1, 1, 5, 6, 10, 11, 19, 20, 29, 33, 38, 43, 56, 60, 76, 81, 90, 98, 118, 121, 138, 147, 163, 172, 197, 202, 230, 243, 260, 273, 294, 303, 336, 352, 373, 384, 421, 430, 470, 487, 508, 528, 572, 583, 623, 640

Offset: 0

Author

Indranil Ghosh, Nov 30 2016

Keywords

• nonn

Links

• Indranil Ghosh and Chai Wah Wu, Table of n, a(n) for n = 0..10000 (terms n = 0..200 from Indranil Ghosh)

Crossrefs

Cf. A278846.

Programs

Python

def a(n):
    s=0
    for a in range(0, n+1):
        for b in range(0, n+1):
            for c in range(0, n+1):
                for d in range(0, n+1):
                    if (a!=b  and a!=d and b!=d and c!=a and c!=b and c!=d):
                        if abs(a*d-b*c)==1:
                            s+=1
    return s
print([int(a(n)/8) for n in range(0, 52)]) # Indranil Ghosh, Nov 30 2016