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

154, 282674, 3003599678

Offset

1,1

References

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

Links

Table of n, a(n) for n=1..3.

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.

Prog

(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); }

Crossrefs

Subsequence of A377732 and A377733.

Sequence in context: A227977 A282557 A200709 * A368138 A248657 A159258

Adjacent sequences: A377733 A377734 A377735 * A377737 A377738 A377739

Keyword

nonn,more,bref

Author

Amiram Eldar, Nov 05 2024

Status

approved