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 A034111 Decimal part of square root of a(n) starts with 5: first term of runs. 1
 21, 31, 43, 57, 73, 91, 111, 133, 157, 183, 211, 241, 273, 307, 343, 381, 421, 463, 507, 553, 601, 651, 703, 757, 813, 871, 931, 993, 1057, 1123, 1191, 1261, 1333, 1407, 1483, 1561, 1641, 1723, 1807, 1893, 1981, 2071, 2163, 2257, 2353, 2451, 2551, 2653 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Agrees with sequence A002061 (n^2-n+1 = central polygonal numbers) starting with sixth term. LINKS Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA a(n) = n^2 + 9*n + 21. - Charles R Greathouse IV, Aug 10 2010 PROG (PARI) a(n)=n^2+9*n+21 \\ Charles R Greathouse IV, Jun 17 2017 CROSSREFS Cf. A034101. Sequence in context: A168000 A031889 A034101 * A077687 A113762 A032585 Adjacent sequences:  A034108 A034109 A034110 * A034112 A034113 A034114 KEYWORD nonn,base,easy AUTHOR Patrick De Geest, Sep 15 1998 STATUS approved

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Last modified January 29 11:16 EST 2020. Contains 331337 sequences. (Running on oeis4.)