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 A255260 a(n) = a(n-1) + sum of the pentagonal numbers which are among the first (n-1) terms of the sequence, with a(1)=1. 3
 1, 2, 3, 4, 5, 11, 17, 23, 29, 35, 76, 117, 275, 433, 591, 749, 907, 1065, 1223, 1381, 1539, 1697, 1855, 2013, 2171, 2329, 2487, 2645, 2803, 2961, 3119, 3277, 3435, 3593, 3751, 3909, 4067, 4225, 4383, 4541, 4699, 4857, 5015, 5173, 5331, 5489, 5647, 5805 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Colin Barker, Table of n, a(n) for n = 1..1000 EXAMPLE a(7) = 17 because a(6) = 11, pentagonal numbers already in the sequence are 1 and 5, and 11+1+5 = 17. PROG (PARI) vector(100, n, if(n==1, a_n_1=sum_=1, a_n_1+=sum_; if(ispolygonal(a_n_1, 5), sum_+=a_n_1)); a_n_1) CROSSREFS Cf. A100963, A101135, A255261. Sequence in context: A104420 A188532 A181288 * A052418 A051800 A121432 Adjacent sequences:  A255257 A255258 A255259 * A255261 A255262 A255263 KEYWORD nonn AUTHOR Colin Barker, Feb 19 2015 STATUS approved

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Last modified February 20 04:34 EST 2020. Contains 332063 sequences. (Running on oeis4.)