A377736 Numbers k such that k, k+1 and k+2 are all terms in A377732.

154, 282674, 3003599678

Offset: 1

Author

Amiram Eldar, Nov 05 2024

Keywords

• nonn
• more
• bref

References

• 144544673718847655 and 10931129469745989328319 are also terms (De Koninck et al., 2024, section 6).

Links

• Jean-Marie De Koninck, A. Arthur Bonkli Razafindrasoanaivolala, and Hans Schmidt Ramiliarimanana, Integers with a sum of co-divisors yielding a square, Research in Number Theory, Vol. 10, No. 2 (2024), Article 30; author's copy.

Crossrefs

Subsequence of A377732 and A377733.

Programs

PARI

is1(k) = if(issquare(k), issquare(2 * sqrtint(k)), my(d = divisors(k), nh = #d/2); issquare(d[nh] + d[nh + 1]));
lista(kmax) = {my(q1 = is1(1), q2 = is1(2), q3); for(k = 3, kmax, q3 = is1(k); if(q1 && q2 && q3, print1(k-2, ", ")); q1 = q2; q2 = q3);}