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A092403 a(n) = sigma(n) + sigma(n+1). 7
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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

LINKS

Table of n, a(n) for n=1..60.

FORMULA

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

MATHEMATICA

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

PROG

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

CROSSREFS

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

Sequence in context: A288374 A308199 A310722 * A219051 A310723 A102737

Adjacent sequences: A092400 A092401 A092402 * A092404 A092405 A092406

KEYWORD

nonn

AUTHOR

Jon Perry, Mar 22 2004

STATUS

approved

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Last modified December 9 23:05 EST 2022. Contains 358710 sequences. (Running on oeis4.)