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 A256718 a(n) = n*(n+1)*(7*n-6)/2. 2
 0, 1, 24, 90, 220, 435, 756, 1204, 1800, 2565, 3520, 4686, 6084, 7735, 9660, 11880, 14416, 17289, 20520, 24130, 28140, 32571, 37444, 42780, 48600, 54925, 61776, 69174, 77140, 85695, 94860, 104656, 115104, 126225, 138040, 150570, 163836, 177859, 192660 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 REFERENCES E. Deza and M. M. Deza, Figurate numbers, World Scientific Publishing (2012), page 93 (21st row of the table). LINKS Bruno Berselli, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1). FORMULA G.f.: x*(1 + 20*x)/(1 - x)^4. a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) with n>3, a(0)=0, a(1)=1, a(2)=24, a(3)=90. a(n) = Sum_{i=0..n-1} (n-i)*(21*i+1) for n>0. MATHEMATICA Table[n (n + 1) (7 n - 6)/2, {n, 0, 40}] PROG (PARI) vector(40, n, n--; n*(n+1)*(7*n-6)/2) (Sage) [n*(n+1)*(7*n-6)/2 for n in (0..40)] (MAGMA) [n*(n+1)*(7*n-6)/2: n in [0..40]]; CROSSREFS Partial sums of A051875. Cf. similar sequences listed in A237616. Sequence in context: A305888 A233644 A010012 * A233637 A179962 A076799 Adjacent sequences:  A256715 A256716 A256717 * A256719 A256720 A256721 KEYWORD nonn,easy AUTHOR Bruno Berselli, Apr 09 2015 STATUS approved

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Last modified February 21 23:28 EST 2019. Contains 320381 sequences. (Running on oeis4.)