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A075683
2nd differences of A075681.
2
2, 17, 20, 22, 25, 28, 31, 34, 37, 40, 43, 46, 49, 52, 55, 58, 61, 64, 67, 70, 73, 76, 79, 82, 85, 88, 91, 94, 97, 100, 103, 106, 109, 112, 115, 118, 121, 124, 127, 130, 133, 136, 139, 142, 145, 148, 151, 154, 157, 160, 163, 166, 169, 172, 175, 178, 181, 184, 187, 190, 193, 196
OFFSET
1,1
FORMULA
From G. C. Greubel, Jan 02 2024: (Start)
a(n) = 2*a(n-1) - a(n-2), for n >= 6.
a(n) = A075681(n+2) - 2*A075681(n+1) + A075681(n).
a(n) = A075682(n+1) - A075682(n).
a(n) = 3*n + 10 - 11*[n=1] + [n=2] + [n=3].
G.f.: x*(2 + 13*x - 12*x^2 - x^3 + x^4)/(1 - x)^2.
E.g.f.: (10 + 3*x)*exp(x) - 10 - 11*x + x^2/2! + x^3/3!. (End)
MATHEMATICA
Join[{2, 17, 20}, 10+3*Range[4, 70]] (* G. C. Greubel, Jan 02 2024 *)
PROG
(Magma) [2, 17, 20] cat [3*n+10: n in [4..70]]; // G. C. Greubel, Jan 02 2024
(SageMath) [2, 17, 20]+[3*n+10 for n in range(4, 71)] # G. C. Greubel, Jan 02 2024
CROSSREFS
Sequence in context: A240475 A107139 A042055 * A340044 A309055 A157191
KEYWORD
nonn,easy
AUTHOR
Jon Perry, Oct 12 2002
EXTENSIONS
Terms a(11) onward added by G. C. Greubel, Jan 02 2024
STATUS
approved