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 A133205 Fully multiplicative with a(p) = p*(p+1)/2 for prime p. 0
 1, 3, 6, 9, 15, 18, 28, 27, 36, 45, 66, 54, 91, 84, 90, 81, 153, 108, 190, 135, 168, 198, 276, 162, 225, 273, 216, 252, 435, 270, 496, 243, 396, 459, 420, 324, 703, 570, 546, 405, 861, 504, 946, 594, 540, 828, 1128, 486, 784, 675, 918, 819, 1431, 648, 990, 756 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS There are analogs with the triangular numbers replaced by some other sequence, but this was chosen because of the parity coincidences of A034953. LINKS FORMULA a((p_1)^e_1)*(p_2)^e_2)*...*(p_k)^e_k)) = (T((p_1))^e_1)*T((p_2))^e_2)*...*T((p_k))^e_k, where T(i) = A000217(i). a(p_i) = A034953(i). PROG (PARI) a(n)=my(f=factor(n)); prod(i=1, #f[, 1], binomial(f[i, 1]+1, 2)^f[i, 2]) /* Charles R Greathouse IV, Sep 09 2010 */ CROSSREFS Cf. A000040, A000217, A003958, A003959, A003960, A003961, A003964, A034953. Sequence in context: A276381 A259728 A000741 * A049991 A143981 A031940 Adjacent sequences:  A133202 A133203 A133204 * A133206 A133207 A133208 KEYWORD mult,easy,nonn AUTHOR Jonathan Vos Post, Oct 10 2007 STATUS approved

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Last modified August 4 06:07 EDT 2020. Contains 336201 sequences. (Running on oeis4.)