A092403 a(n) = sigma(n) + sigma(n+1).

4, 7, 11, 13, 18, 20, 23, 28, 31, 30, 40, 42, 38, 48, 55, 49, 57, 59, 62, 74, 68, 60, 84, 91, 73, 82, 96, 86, 102, 104, 95, 111, 102, 102, 139, 129, 98, 116, 146, 132, 138, 140, 128, 162, 150, 120, 172, 181, 150, 165, 170, 152, 174, 192, 192, 200, 170, 150, 228, 230

Offset: 1

Author

Jon Perry, Mar 22 2004

Keywords

• nonn

Comments

a(n) is the area of the terrace in the level 1 of the polycube called "tower" described in A221529 where the longest side of its base is equal to n + 1, thus a(n) has a symmetric representation. - Omar E. Pol, Jul 22 2021

Crossrefs

Cf. A000203, A092405, A221529, A237593, A346533.

Programs

Mathematica

Total/@Partition[DivisorSigma[1,Range[70]],2,1] (* Harvey P. Dale, Feb 19 2018 *)

PARI

for(i=1,60,print1(","sigma(i)+sigma(i+1)))

Formula

a(n) = A346533(n+1,n). - Omar E. Pol, Jul 22 2021