A371381 Main diagonal of A219875.

2, 8, 13, 25, 41, 52, 74, 89, 117, 149, 170, 208, 250, 277, 325, 356, 410, 468, 505, 569, 610, 680, 754, 801, 881, 965, 1018, 1108, 1165, 1261, 1361, 1424, 1530, 1640, 1709, 1825, 1898, 2020, 2146, 2225, 2357, 2440, 2578, 2720, 2809, 2957, 3109, 3204, 3362, 3461

Offset

1,1

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Formula

a(n) = n^2 + ceiling(n/(1 + sqrt(5))/2)^2 = n^2 + A019446(n)^2.

Mathematica

Array[#^2 + Ceiling[# / GoldenRatio]^2 &, 100]

Prog

(Python)
from math import isqrt
def A371381(n): return (n<<1)*(n-1)+1+(q:=n+isqrt(5*n**2)>>1)*(q-(n-1<<1)) # Chai Wah Wu, Mar 21 2024

Crossrefs

Cf. A219875.

Cf. A001622, A019446, A101332, A101863, A101867, A371382.

Sequence in context: A271383 A193666 A196024 * A037382 A297810 A298142

Adjacent sequences: A371378 A371379 A371380 * A371382 A371383 A371384

Keyword

nonn,easy

Author

Paolo Xausa, Mar 20 2024

Status

approved