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A325301
a(n) is the number of edges of the stepped pyramid with n levels described in A245092.
3
12, 21, 36, 51, 63, 84, 96, 117, 138, 165, 177, 204, 216, 240, 273, 306, 318, 351, 363
OFFSET
1,1
COMMENTS
To calculate a(n) consider that levels greater than n do not exist.
FORMULA
a(n) = A325300(n) + A325302(n) - 2 (Euler's formula).
EXAMPLE
For n = 1 the first level of the stepped pyramid (starting from the top) is a cube, and a cube has 12 edges, so a(1) = 12.
CROSSREFS
Cf. A325300 (number of faces), A325302 (number of vertices).
Sequence in context: A071263 A241503 A226186 * A351478 A219542 A354984
KEYWORD
nonn,more
AUTHOR
Omar E. Pol, Apr 16 2019
STATUS
approved