

A091522


GrahamPollak sequence with initial term 5.


4



5, 7, 10, 14, 20, 28, 40, 57, 81, 115, 163, 231, 327, 463, 655, 927, 1311, 1854, 2622, 3708, 5244, 7416, 10488, 14832, 20976, 29665, 41953, 59331, 83907, 118663, 167815, 237326, 335630, 474653, 671261, 949307, 1342523, 1898614, 2685046
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OFFSET

1,1


LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..500
Th. Stoll, On Families of Nonlinear Recurrences Related to Digits, Journal of Integer Sequences, Vol. 8 (2005), Article 05.3.2.
Eric Weisstein's World of Mathematics, GrahamPollak Sequence


FORMULA

a(n) = floor(sqrt(2) * (a(n1) + 1/2)).


MATHEMATICA

NestList[Floor[Sqrt[2](#+1/2)]&, 5, 40] (* Harvey P. Dale, Feb 24 2018 *)


PROG

(PARI) first(n)=my(v=vector(n)); v[1]=5; for(k=2, n, v[k]=sqrtint(2*(v[k1]+1)*v[k1])); v \\ Charles R Greathouse IV, Jan 23 2020


CROSSREFS

Cf. A001521, A091523.
Sequence in context: A190035 A071911 A070875 * A020711 A183044 A133756
Adjacent sequences: A091519 A091520 A091521 * A091523 A091524 A091525


KEYWORD

nonn


AUTHOR

Eric W. Weisstein, Jan 18 2004


STATUS

approved



